Prof.
Leonardo Giusti
(University of Milano Bicocca)
14/07/2015, 09:15
I review recent progress achieved on the lattice in the understanding of chiral symmetry breaking in QCD. Emphasis is given to recent computations of the spectral density of the Dirac operator and of the topological susceptibility.
Dr
Tatsumi Aoyama
(KMI, Nagoya University)
14/07/2015, 11:00
Talk
The anomalous magnetic moment (g-2) of the electron has played the central role in testing the validity of quantum electrodynamics (QED) as well as the standard model of particle physics. The test has been further improved, which was made possible by the complete evaluation of the tenth-order term in the perturbation theory of QED, together with the latest measurement of the electron g-2 by...
Taku Izubuchi
(RIKEN BNL Research Center)
14/07/2015, 11:45
There has been much progress in studies of the physics of low energy, precision observables in the flavor neutral sector using Lattice QCD, especially on the lepton anomalous magnetic moments ($g-2$) and nucleon electric dipole moments. The current status of these studies is reviewed, and remaining challenges and new ideas are discussed.
Stefan Sint
(Trinity College Dublin)
14/07/2015, 14:00
The ALPHA collaboration has set itself the goal to determine alpha_s(m_Z) with a total error substantially below the percent level. A further step towards this goal can be taken by combining results from the recent simulations of 2+1 flavour QCD by the CLS initiative with a number of tools developed over the years: renormalized couplings in finite volume schemes, recursive finite size...
Mr
Greg McGlynn
(Columbia University)
14/07/2015, 14:00
We discuss algorithmic improvements being used in the evolution of new 2+1+1 flavor lattices by the RBC/UKQCD collaboration. A technique similar to Hasenbusch mass splitting and suggested previously by Brower, Neff, and Orginos allows the light quark action to be split into multiple parts with different values of L_s, the size of the fifth dimension. This allows us to reduce chiral symmetry...
Mr
Luchang Jin
(Columbia University)
14/07/2015, 14:00
The current measurement of muonic g-2 disagrees with the theoretical calculation by about 3 standard deviations. Hadronic vacuum polarization (HVP) and hadronic light by light (HLbL) are the two types of processes that contribute most to the theoretical uncertainty. The current value for HLbL is still given by a model . In this talk, I will describe results from a first-principles lattice...
Ben Hörz
(School of Mathematics, Trinity College Dublin)
14/07/2015, 14:00
We present results on pion-pion scattering in the isovector channel from N_f = 2+1 CLS simulations with open temporal boundary conditions and m_\pi = 280 MeV. The required correlation functions are computed using the stochastic LapH method that facilitates large-volume calculations in order to maintain m_\pi L > 4. Mapping out the \rho resonance structure is a necessary step towards the...
Dr
Prasad Hegde
(Central China Normal University)
14/07/2015, 14:00
The QCD chiral phase transition for small values of baryon chemical potentials is expected to be second-order and the dependence of its transition temperature on the chemical potentials is thus controlled by the dependence of $O(N)$ scaling functions on the reduced temperature variables. Though the transition is merely a crossover at physical quark mass, the dependence of the chiral phase...
Dr
John Bulava
(Trinity College Dublin)
14/07/2015, 14:20
Results for pion-pion scattering phase shifts using the stochastic
LapH method on a single $N_f = 2+1$ anisotropic clover lattice with
$m_{\pi}\equiv 240\mathrm{MeV}$ and $L\equiv 3.8\mathrm{fm}$ will be presented. In particular, for $I=1$ this large volume enables good resolution of the $\rho$ resonance shape. Prospects for the other isospin channels will also be discussed.
Mr
Masashi Hayakawa
(Nagoya University)
14/07/2015, 14:20
The first-principles calculation of the hadronic light-by-light scattering (HLbL) contribution is the most critical issue in the theory of the muon $g-2$ to confront the standard model prediction with the more accurate experimental result to be provided in the next five years. The feasibility of the lattice QCD computation of the HLbL contribution has been demonstrated for the “connected...
Dr
Patrick Fritzsch
(Instituto de Física Teoríca UAM/CSIC)
14/07/2015, 14:20
We present the current status of a revised strategy to compute the running of renormalized quark masses in QCD with three flavours of massless O(a) improved Wilson quarks. The strategy employed uses the standard finite-size scaling method in the Schroedinger functional and accommodates for the non-perturbative scheme-switch which becomes necessary at intermediate renormalized couplings as...
Ms
Jana Guenther
(Wuppertal University)
14/07/2015, 14:20
An efficient way to study the QCD phase diagram at small finite density
is to extrapolate thermodynamical observables from imaginary chemical potential.
The phase diagram features a crossover line starting from the
transition temperature already determined at zero chemical potential.
In this talk we focus on the curvature of this line at mu = 0. We present
the extrapolation of the...
Dr
Ed Bennett
(Swansea University)
14/07/2015, 14:20
SU(3) gauge theory with eight massless flavours is believed to be walking, while the corresponding twelve- and four-flavour appear IR-conformal and confining respectively. Looking at the simulations performed by the LatKMI collaboration of these theories, we use the topological susceptibility as an additional probe of the IR dynamics. By drawing a comparison with SU(3) pure gauge theory, we...
Chulwoo Jung
(Brookhaven National Laboratory)
14/07/2015, 14:20
Recent advances in hardware, combined with various deflation techniques has made it crucial to optimize not only for solver performances, but also for memory and disk footprint to keep the overall efficiency high.
Here we report on advances in Domain Wall Fermion formalism(DWF), such as zMobius which achieves a good approximation to the scaled Shamir DWF with smaller extent in 5th...
Dr
Leonardo Cosmai
(INFN)
14/07/2015, 14:40
We study QCD with (2 + 1) HISQ fermions at nonzero temperature
and nonzero imaginary baryon chemical potential.
Monte Carlo simulations are performed using the MILC code
along the line of constant physics with a light to strange mass ratio of ml/ms=1/20
on lattices up to 48^3x12 to check for finite cutoff effects.
We determine the curvature of the pseudocritical line extrapolated to...
Mr
Andrea Bussone
(CP3-Origins, University of Southern Denmark)
14/07/2015, 14:40
Imposing twisted boundary conditions on the fermion fields is a procedure extensively used when evaluating, for example, form factors on the lattice. Twisting is usually performed for one flavour and only in the valence, and this causes a breaking of unitarity.
In this work we explore the possibility to restore the unitarity through the reweighting method. We evaluate the change in the...
Christoph Lehner
(BNL)
14/07/2015, 14:40
We explore methods to improve the volume-dependence of lattice QCD+QED simulations. Applications to QED mass-splittings, QED corrections to decay constants, and the computation of the hadronic light-by-light contribution to the muon anomalous magnetic moment are discussed.
Mr
Tadeusz Janowski
(University of Southampton)
14/07/2015, 14:40
I will present preliminary results on K-pi scattering lengths in both I=3/2 and I=1/2 channels obtained by the RBC-UKQCD collaboration. The continuum results are obtained using two of our Moebius domain wall fermion ensembles - 48^3 x 96 and 64^3 x 128 - with physical quark masses.
I will demonstrate how the large finite time extent effects which are present with such light quark masses can...
Mr
David Preti
(Instituto de Física Teoríca UAM/CSIC)
14/07/2015, 14:40
We present preliminary results for the non-perturbative renormalization of the tensor current in QCD for $N_f=0,2$, as well as an ongoing extension to $N_f=2+1$. The renormalization group running is computed in the continuum limit for a wide range of scales, using various Schrodinger Functional (SF) schemes and finite volume recursive techniques. In all these schemes, we have also computed the...
Michele Mesiti
(Universita' di Pisa)
14/07/2015, 15:00
We present our latest results on the determination of the curvature of the pseudo-critical line of the QCD phase diagram at the physical point, using the method of analytic continuation from an imaginary chemical potential. We also assess the impact of including a non-zero strange quark chemical potential. Our results are obtained with stout improved staggered fermions and the tree level...
Dr
Gordon Donald
(University of Regensburg)
14/07/2015, 15:00
Results will be presented for pi-pi and K-pi scattering using lattice configurations on which the pion mass is 150 MeV.
In this study the focus is on the kinematic region around the rho (for pi-pi scattering) and K* (for K-pi) resonances.
Different lattice volumes and moving frames are used to obtain the spectrum for a range of centre of mass energies, which allows the energy dependence of...
Dr
Meifeng Lin
(Brookhaven National Laboratory)
14/07/2015, 15:00
The application of the Dirac operator on a spinor field, the Dslash operation, is the most computation-intensive part of the lattice QCD simulations. It is often the key kernel to optimize to achieve maximum performance on various platforms. Here we report on a project to optimize the domain wall fermion Dirac operator in Columbia Physics System (CPS) using the R-Stream source-to-source...
Stefan Schaefer
(NIC, DESY)
14/07/2015, 15:00
During the last two years, the CLS effort has generated ensembles with 2+1 dynamical flavors of non-perturbatively improved Wilson fermions at lattice spacings between 0.05fm and 0.09fm. Most of these ensembles are along lines of constant sum of bare sea quark masses tr(M). We give an overview of these simulations and describe our scale setting procedure using the pseudoscalar decay constants....
Prof.
Claudio Rebbi
(Boston University)
14/07/2015, 15:00
After a brief review of the motivation for studying an SU(3) theory
with four light flavors and eight flavors of variable mass I will
discuss the methodologies we have used to investigate the properties
of the system. I will then illustrate some recent results. More
detailed results will be given in another talk. We will also
illustrate some results of a study of the SU(3) theory with...
Mr
Matt Spraggs
(University of Southampton)
14/07/2015, 15:00
We present preliminary results for the strange leading-order hadronic contribution to the anomalous magnetic moment of the muon using RBC/UKQCD physical point domain wall fermions ensembles. We discuss various analysis strategies in order to constrain the systematic uncertainty in the final result.
Prof.
Peter Boyle
(University of Edinburgh)
14/07/2015, 15:20
We discuss progress and performance from the development of a
data parallel interface for cartesian fields of tensor data types. The
library is suitable for the simulation of QCD including multiple grids.
Wherever appropriate the interface is quite similar to that of QDP++,
but the library makes use of C++11 features to reduce the volume of code,
compared to QDP++ while bringing...
Dr
Antonin Portelli
(University of Southampton)
14/07/2015, 15:20
The muon anomalous magnetic moment constitute one of the most important tension between experimental measurements and the Standard Model predictions. The dominant theoretical uncertainties is coming from hadronic contributions, therefore it is crucial to aim at determining precisely and reliably this quantity from lattice QCD. Most of the contributions to the leading hadronic contribution...
Dr
Pol Vilaseca Mainar
(Instituto Nazionale de Fisica Nucleare)
14/07/2015, 15:20
The chirally rotated Schrödinger functional (χSF) is a renormalization scheme which renders the mechanism of automatic O(a) improvement compatible with the Schrödinger functional (SF) formulation.
Here we define a family of renormalization schemes based on the χSF for a complete basis of ∆S = 2 parity-odd four-fermion operators.
We compute the scale-dependant renormalization constants of...
Dr
Shinji TAKEDA
(Kanazawa university)
14/07/2015, 15:20
We investigate the phase structure of finite temperature and density QCD with three-flavor by using Wilson-Clover fermions. We focus on locating the critical end point that characterizes the phase structure and extracting the curvature of critical line on the plane of quark chemical potential and pseudo-scalar meson mass.
Evan Weinberg
(Boston University Department of Physics)
14/07/2015, 15:20
We investigate an SU(3) gauge theory with four light flavors and eight heavy flavors of variable mass as a model of near conformal dynamics. By continuously varying the mass of the eight heavy flavors we can tune between chirally broken and conformal behavior. We report on recent progress with probing this model deeper in the light flavor chiral regime, including updated measurements of a...
Prof.
ying chen
(institute of high energy physics, chinese academy of sciences, china)
14/07/2015, 15:20
We use overlap valence quarks on the $L^3\times T=48^3\times 96$ $N_f=2+1$ domain-wall fermion configurations generated by the RBC\&UKQCD Collaboration. The light sea quark mass is at the physical point and the spatial extension is 5.5 fm. The $\rho$ mass is precisely determined to be $m_\rho=778(9)$ MeV at the physical pion mass. We also propose a strategy to reduce the noise of the wall-wall...
Ms
bipasha Chakraborty
(University of Glasgow)
14/07/2015, 15:40
We report our (HPQCD) progress with the lattice QCD calculations of both the connected and disconnected hadronic Vacuum Polarisation (HVP) contributions to the anomalous magnetic moment of the muon (g-2). Our method uses Padé approximants to reconstruct the Adler function from its derivatives at q^2=0. These are obtained simply and accurately from time-moments of the vector current-current...
Mr
Ryo IWAMI
(Niigata University)
14/07/2015, 15:40
We discuss the QCD critical point at finite density through the study of many-flavor QCD, in which two light flavors and Nf massive flavors exist. Performing simulations of QCD with 2 flavors of improved Wilson fermions, we calculate probability distribution functions in many-flavor QCD at finite temperature and density, where the reweighting technique is used to add the dynamical effect of...
Mr
Dehua Guo
(The George Washington University)
14/07/2015, 15:40
We present a lattice calculation of the mass and width for the rho meson by determining the energy dependent phaseshift for pi-pi scattering in isospin-1, spin-1 channel in the elastic region. We compute the energy spectrum from spatially asymmetric boxes. We use Nf=2 nHYP fermions and generate two sets of ensembles with pion masses of 300MeV and 220MeV. To determine the energy spectrum we...
Dr
Mattia Dalla Brida
(DESY - Zeuthen)
14/07/2015, 15:40
The chirally rotated Schrödinger functional has proven to be a powerful tool in addressing non-perturbative renormalization problems in lattice QCD with Wilson-type fermions. In this contribution we consider two novel applications of the method. Firstly, we investigate the renormalization of a complete basis of ΔS=2 four-quark operators relevant for searches of Beyond the Standard Model...
Prof.
Julius Kuti
(U.C. San Diego)
14/07/2015, 16:30
A low mass scalar state has been observed by the Lattice Higgs Collaboration as a viable candidate for the minimal realization of the composite Higgs from a fermion doublet in the two-index symmetric representation of the SU(3) color gauge group. The difficulty of decoupling Goldstone dynamics from the low mass scalar state in realistic simulations requires the extension of the low energy...
Dr
Jeremy Green
(Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
14/07/2015, 16:30
Calculations of hadronic light-by-light scattering amplitudes via lattice QCD evaluation of Euclidean four-point functions of vector currents will be reported. These initial results include only the fully quark-connected contribution. Particular attention will be given to the case of forward scattering, which can be related via dispersion relations to the gamma* gamma* -> hadrons cross...
Dr
Piotr Korcyl
(University of Regensburg)
14/07/2015, 16:30
We report on progress to renormalize non-perturbatively the static heavy quark theory on the lattice. In particular, we present first results for position-space renormalization scheme for heavy-light bilinears. We test our approach on RBC's 16^3 x 32 lattice ensemble with pion mass of 420 MeV, Iwasaki gauge action and domain wall light fermions.
Naoya Ukita
(University of Tsukuba)
14/07/2015, 16:50
We present our preliminary results on 2+1 flavor QCD with the stout smeared O(a)-improved Wilson quark action and the Iwasaki gauge action. Simulations are carried out at a lattice spacing 0.085fm on a $96^4$ lattice with the quark masses near the physical point. The reweighing technique and ChPT are employed for the extrapolation to the physical point. We will show the preliminary results of...
Mr
wong chik him
(university of wuppertal)
14/07/2015, 16:50
The SU(3) gauge theory with two flavors of two-index symmetric (sextet) fermions has been of great interest recently since a low-mass scalar meson that may serve as a composite Higgs candidate was observed in our previous studies. The hadron spectrum analysis on a more extended dataset will be presented as a followup investigation.
Mr
Christian Wittemeier
(University of Muenster, Germany)
14/07/2015, 16:50
We outline our strategy to non-perturbatively match all components of the heavy-light axial and vector currents in Heavy Quark Effective Theory (HQET) at O(1/m) to finite-volume lattice QCD. Based on a tree-level study, we propose a set of matching conditions between suitable observables defined in QCD and HQET to fix the parameters of the effective theory, which are required to absorb the...
Prof.
Christopher Sachrajda
(University of Southampton)
14/07/2015, 16:50
We review the method proposed in [1] to compute electromagnetic effects in
hadronic processes, such as decays, using lattice simulations. The method
can be applied, for example, to the leptonic and semileptonic decays of light
or heavy pseudoscalar mesons. For these quantities the presence of infrared
divergences in intermediate stages of the calculation makes the procedure
much more...
Gregorio Herdoiza
(IFT UAM-CSIC)
14/07/2015, 16:50
The electromagnetic coupling receives significant contributions to its
running from non-perturbative QCD effects. We present an update of our
study of the Adler function and of its application to the
determination of leading order hadronic contribution to the running of
the QED coupling. We use a high-statistics lattice QCD computation
with two flavours of O(a) improved Wilson fermions...
Mr
Christopher Czaban
(Goethe University Frankfurt am Main)
14/07/2015, 16:50
The chiral and deconfinement phase transitions
at zero density for light and heavy quarks, respectively, have
analytic continuations to imaginary chemical potential. At some
critical imaginary chemical potential, they meet the high temperature
Roberge-Weiss transition between adjacent Z3 sectors.
For light and heavy
quarks, where the chiral and deconfinement transitions are first...
Dr
Wolfgang Soeldner
(Regensburg University)
14/07/2015, 17:10
We will report on latest results of the RQCD group obtained from 2+1f gauge field configurations with non-perturbatively improved Wilson action and open boundaries generated within the CLS effort. We have extended our simulations to include two chiral trajectories, one keeping the average quark mass fixed and an additional one where the strange quark mass is kept at its physical value. For the...
Dr
Renwick Hudspith
(York University, Toronto)
14/07/2015, 17:10
We compute the hadronic matrix elements of the four-quark operators needed for the study of $K^0-{\bar K^0}$ mixing beyond the Standard Model (SM). We have used $n_f=2+1$ flavours of domain wall fermion (DWF) at two values of the lattice spacing ($a\approx0.08$ and $a\approx0.11\text{fm}$) and with lightest unitary Pion mass of $\approx300\,\text{MeV}$. Renormalisation is performed...
Prof.
Francesco Knechtli
(University of Wuppertal)
14/07/2015, 17:10
We simulate a theory with N_f=2 heavy quarks of mass M. At energies much
smaller than M the heavy quarks decouple and the theory can be described
by an effective theory which is a pure gauge theory to leading order in 1/M. We present results for the mass dependence of ratios such as t_0(M)/t_0(0). We compute these ratios from simulations and compare them to the perturbative prediction. The...
Mr
santanu Mondal
(Eötvös Loránd University)
14/07/2015, 17:10
We show the cutoff dependence of taste symmetry breaking on the full staggered Goldstone spectrum in the sextet model.
Taste symmetry in the Goldstone valence spectrum is restored using a mixed action setup on the gauge field gradient flow.
Dr
Christopher Pinke
(Goethe University Frankfurt)
14/07/2015, 17:10
The clarification of the order of the thermal transition in the chiral limit of QCD with two dynamical flavours of quarks is a long-standing issue. Still, it is not definitely known if the transition is of first or second order. Which of the two scenarios is realized has important implications for the physical QCD phase diagram, and in particular it is important regarding the existence of a...
Prof.
Hiroshi Yoneyama
(Saga University)
14/07/2015, 17:30
Finite density and temperature QCD with heavy quarks is studied
in the complex chemical potential ($¥mu$) plane by use of a mean field method and Monte Carlo simulations, where the former applies to the strong coupling region.
We calculate the effective potential as a function of Polyakov line, and study thermodynamic singularities and their associated Stokes lines in the complex $¥mu$...
Dr
Hidenori Fukaya
(Osaka University)
14/07/2015, 17:30
Calculation of the eta-prime mass is a notoriously difficult problem, as it requires evaluation of the disconnected diagram which is costly and noisy. In this work, we use a gluonic operator to extract the eta-prime state after smearing the link variables through the Wilson flow. With this choice, one can avoid a large cancellation of pion contribution between the connected and disconnected...
Prof.
Maarten Golterman
(San Francisco State University)
14/07/2015, 17:30
We investigate finite volume effects in the hadronic vacuum polarization,
with an eye toward the corresponding systematic error in the muon
anomalous magnetic moment. While it is well known that leading-order
chiral perturbation theory does not provide a good description of the
hadronic vacuum polarization, it turns out that it gives a much better
representation of finite volume...
Mr
Jack Dragos
(University of Adelaide)
14/07/2015, 17:30
Calculating hadronic matrix elements in Lattice QCD that are relevant for e.g. Form Factors and Parton Distribution Functions, provides important insights into the structure of hadrons. However standard 3-point function methods have their limitations. One of the most commonly studied sources of systematic error is excited state contamination, which occurs when correlators are contaminated with...
225.
Nonperturbative renormalization in the RI-SMOM scheme and Gribov copies for staggered bilinears
Mr
Sungwoo Park
(Seoul National University)
14/07/2015, 17:30
We present renormalization factors for the bilinear operators obtained using the nonperturbative renormalization method (NPR) in RI-SMOM scheme for improved staggered fermions on the MILC asqtad lattice (Nf=2+1). We compare the RI-SMOM result to the RI-MOM scheme result and the one-loop perturbative result. Since the NPR requires Landau gauge fixing, we study related Gribov copy problem in...
Daniel Nogradi
(Eotvos University)
14/07/2015, 17:30
The renormalized running coupling of SU(3) gauge theory coupled to Nf = 2 flavors of massless Dirac fermions in the 2-index-symmetric (sextet) representation is calculated. This model is of particular interest as a minimal realization of the strongly interacting composite Higgs scenario. A recently proposed finite volume gradient flow scheme is used. The calculations are
performed at several...
Dr
Eric Gregory
(Bergische Universitaet Wuppertal & Juelich Supercomputing Centre)
14/07/2015, 17:50
We describe a lattice approach to calculate the leading-order anomalous
magnetic moment of the muon. We employ lattice momentum derivatives to
determine the hadronic vacuum polarization scalar at low momenta and
construct a smooth, intregrable function in this momentum region. We present preliminary results for hex-smeared Wilson-quark lattice ensembles.
Mr
Martin Hansen
(CP3-Origins, University of Southern Denmark)
14/07/2015, 17:50
We present new results from our simulations of the SU(3) "sextet model" with two flavors in the 2-index symmetric representation of the gauge group. The simulations use unimproved Wilson fermions and we measure the meson and baryon spectrum of the theory for multiple bare quark masses at two different lattice spacings. To address the ongoing issue of whether the model is inside or outside the...
Dr
Andrew Lytle
(University of Glasgow)
14/07/2015, 17:50
I will report on a calculation of quark bilinear Z-factors for the HISQ action using non-perturbative renormalization techniques. One of the main outputs is the mass renormalization factor Z_m relating bare quark masses to the MSbar scheme. This will provide an independent determination of quark masses in addition to other methods being used by the HPQCD collaboration.
Dr
Thorsten Kurth
(Lawrence Berkeley National Laboratory)
14/07/2015, 17:50
The electroweak interaction on the level of quarks and gluons are well understood from precision measurements in high energy collider experiments.
Relating these fundamental parameters to Hadronic Parity Violation in nuclei however remains an outstanding theoretical challenge. One of the most interesting observables in this respect is the parity violating hadronic neutral current: it is hard...
Dr
Michael Endres
(Massachusetts Institute of Technology)
14/07/2015, 17:50
The commonly adopted approach for including QED in lattice QCD simulations introduces power-law finite volume corrections to physical quantities. These effects, which are due to the long-range nature of the electromagnetic interaction, must be removed by performing simulations at multiple lattice volumes, followed by an extrapolation to the infinite volume limit. In this work, we explore the...
Dr
Kouji Kashiwa
(Yukawa Institute for Theoretical Physics, Kyoto University)
14/07/2015, 17:50
One of the important subjects in QCD is understanding properties of deconfinement transition at finite temperature and density. We investigate the pseudo-critical temperature of the deconfinement transition by considering the complex chemical potential. The imaginary chemical potential can be interpreted as the Aharonov-Bohm phase induced by U(1) flux insertions to the fictitious hole of the...
Dr
Paul Rakow
(University of Liverpool)
14/07/2015, 18:10
We present results on the pseudoscalar meson masses from
a fully dynamical simulation of QCD plus QED. We concentrate
particularly on the question of how to divide the measured
masses into a QED contribution and a QCD contribution.
This decomposition is not unique, it depends on the
renormalisation scheme and scale. We suggest a renormalisation
scheme in which Dashen's theorem...
Prof.
Steven Gottlieb
(Indiana University)
14/07/2015, 18:10
The MILC Collaboration has completed production running of electromagnetic effects on light mesons using asqtad improved staggered quarks. In these calculations, the photons are quenched using the non-compact formalism. Four lattice spacings from 0.12 fm to 0.045 fm have been used. Finite volume effects with $a=0.12$ fm have been studied with spacial sizes $L_s=12$, 16, 20, 28, 40, and 48. ...
Prof.
Tatsuhiro Misumi
(Akita University / Keio University)
14/07/2015, 18:10
By imposing flavor-dependent boundary conditions on quarks,
we construct three-flavour SU(3) gauge theory reconciling fundamental
fermion representation and exact Z3 center symmetry.
In this talk, we show the first result of lattice simulation on this QCD-like theory,
which we call Z3-QCD, with emphasis on the finite-temperature phase
transition with respect to center and chiral...
Dr
Marina Marinkovic
(CERN)
14/07/2015, 18:10
Several leading lattice collaborations are investing significant effort to reduce the uncertainty in the lattice computation of the HVP to a sub-percent level. In order to achieve this goal, giving an estimate of the size of the isospin breaking effects becomes relevant. Recently, the RM123 developed a method for separating QCD from QED isospin breaking effects based on expansion of the...
Dr
James Zanotti
(University of Adelaide)
15/07/2015, 09:00
Here we review the progress made in understanding the internal structure of hadrons in terms of the gluonic and quark constituents. Recent results for standard observables such as the nucleon axial charge, electromagnetic form factors and quark momentum fraction will be summarised, before turning our attention to more challenging quantities, including quark disconnected contributions and...
Dr
Andreas Juettner
(University of Southampton)
15/07/2015, 09:45
For quite some time now simulations of lattice QCD have allowed for predicting a basic set of light flavour quantities reliably and with increasingly high precision. The field has started to move on: Advances in field theory, algorithms and computing for the first time allow to address more complicated problems like for example hadronic and rare kaon decays, the kaon mass-difference or the...
15/07/2015, 11:00
Talk
Dr
Maxwell Hansen
(University of Mainz)
15/07/2015, 11:30
Scattering and transition amplitudes with three-hadron final states play an important role in nuclear and particle physics. In order to predict such quantities using Lattice QCD, formalism is required to overcome the limitations of Euclidean time and finite volume. In this talk I will focus on extensions of Luescher's work relating the finite-volume energy spectrum to physical scattering...
Dr
Christopher Kelly
(RBRC, Brookhaven National Laboratory)
15/07/2015, 12:00
We discuss our recent publication [arXiv:1505.07863] of the first lattice QCD calculation of the complex kaon decay amplitude A_0 with physical kinematics, using a single 32^3 x 64 domain wall ensemble with G-parity spatial boundary conditions. We obtain approximate agreement with the experimental value for Re(A_0), which serves as a test of our method. Our prediction of Im(A_0) can be used to...
d. k. sinclair
(argonne national laboratory)
15/07/2015, 14:00
Recent advances in applying complex-Langevin simulations to gauge theories with complex actions, in particular gauge-cooling, have revived interest in using these methods for QCD at finite baryon-number density. QCD at a finite chemical potential $\mu$ for quark number has a complex fermion determinant which prevents use of standard simulation techniques. Complex-Langevin simulations show...
Kim Maltman
(York University)
15/07/2015, 14:00
Existing versions of the standard determinations of V_us from flavor-breaking finite energy sum rules with hadronic tau decay data as input yield V_us values 3 sigma or more below the expectations of 3-family unitarity. Slow convergence of the D=2 OPE series employed in these sum rules, however, makes it hard to assess the reliability of the use of the OPE representation. In this paper we use...
183.
Lattice study for conformal windows of SU(2) and SU(3) gauge theories with fundamental fermions
Prof.
C.-J. David Lin
(National Chiao-Tung University)
15/07/2015, 14:00
We present results from our study of SU(2) gauge theory with eight flavours, and SU(3) gauge theory with twelve flavours. These two theories may be very close to the lower ends of the conformal windows for the SU(2) and SU(3) gauge groups, respectively, when only the fundamental-representation fermions are present. For the SU(2) theory with eight flavours, we report our investigation for...
Dr
William Detmold
(MIT)
15/07/2015, 14:00
I will discuss the NPLQCD collaboration's recent calculations of the magnetic moments
and polarisabilities of light nuclei up to A=4 using background field methods. I will also describe an a calculation of the magnetic transition amplitude that determines the
$n p \to d \gamma$ cross section that is of central importance in Big Bang Nucleosynthesis.
Prof.
Keh-Fei Liu
(University of Kentucky)
15/07/2015, 14:00
Parton Distribution function can be obtained from calculating
the hadronic tensor on the lattice. It involves a 4-point function evaluation
with two vector or axial-vector currents. We propose to use the source method for
one of the currents and effectively reduce the numerical complexity to that of
a 3-point function. The method can be generalized to evaluate other 4-point functions.
Prof.
Anthony Kennedy
(University of Edinburgh)
15/07/2015, 14:00
Symanzik showed that quantum field theory can be formulated on a space with boundaries by including suitable surface interactions in the action to implement boundary conditions. We show that to all orders in perturbation theory all the divergences induced by these surface interactions can be absorbed by a renormalization of their coefficients.
Sara Tähtinen
(University of Helsinki, Helsinki Institute of Physics)
15/07/2015, 14:20
It is expected that SU(2) gauge theory with N_f fundamental fermions has an infrared fixed point when N_f is between ~6 and 11. We study the hadron spectrum and scale setting in SU(2) gauge field theory with N_f=2,4,6 using hypercubic stout smeared Wilson-clover (HEX) action. The case N_f=2 is QCD-like, whereas N_f=6 is close to the lower edge of the conformal window. In our study length...
Mr
Aleksandr Ivanov
(Faculty of Physics M.V.Lomonosov Moscow State University)
15/07/2015, 14:20
The small coupling expansions in the lattice field theory are asymptotic
and do not converge. It was shown in previous studies, that an appropriate regularization of the integrals or shifting of the initial approximation allows one to construct convergent series.
In this work we study the convergent series in application to the lattice $\phi^4$-model
and compare the observables calculated...
Takeshi Yamazaki
(University of Tsukuba)
15/07/2015, 14:20
We present our result of binding energy of light nuclei
with the nuclear mass number less than or equal to four
at the pion mass m_pi = 0.3 GeV.
The simulations are performed in N_f=2+1 QCD with Iwasaki gauge
and non-perturbative improved Wilson fermion actions at the
lattice spacing of a = 0.09 fm.
We discuss the quark mass dependence of the binding energies
using our previous results...
Dr
Boram Yoon
(Los Alamos National Laboratory)
15/07/2015, 14:20
We present a lattice QCD calculation of transverse momentum dependent parton distributions (TMDs) in the proton using staple-shaped gauge links. We calculate both naively time-reversal odd (T-odd) observables, namely, the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY processes, as well as T-even observables, namely, the transversity related to the tensor charge...
134.
Scalar and vector form factors of $D \to \pi \ell \nu$ decays with $N_f=2+1+1$ Twisted fermions
Mr
Paolo Lami
(Università degli Studi Roma Tre & INFN sezione Roma Tre)
15/07/2015, 14:20
We present lattice results for the form factors relevant for $D \to \pi \ell \nu$ decays, obtained from simulations performed by the European Twisted Mass Collaboration with $N_f=2+1+1$ flavors of dynamical quarks, at three values of the lattice spacing and pion masses as low as $210$ MeV.
We computed both the vector and the scalar form factors, studied their dependance on the momentum...
Mr
Felipe Attanasio
(Swansea University)
15/07/2015, 14:20
Monte Carlo methods cannot probe far into the QCD phase diagram with a real chemical potential, due to the famous sign problem. Complex Langevin simulations, using adaptive step-size scaling and gauge cooling, are suited for sampling path integrals with complex weights. We report here tests on the deconfinement transition in pure Yang-Mills SU(3) simulations and present an update on the QCD...
Mr
Viljami Leino
(University of Helsinki)
15/07/2015, 14:40
SU(2) with Nf=8 flavors of fundamental fermions is expected to feature an infrared fixed point (IRFP). We measure the evolution of the coupling constant with Schrödinger functional boundary conditions and gradient flow, using HEX-smeared Wilson-clover action. We observe clear evidence for a fixed point, qualitatively compatible with perturbative results.
Robert Lohmayer
(University of Regensburg)
15/07/2015, 14:40
We study pure SU(N) lattice gauge theory with a plaquette weight factor given by an inverse determinant which can be written as an integral over auxiliary bosonic fields (modifying a proposal of Budczies and Zirnbauer). We derive conditions for the existence of a continuum limit and its equivalence to Yang-Mills theory. Furthermore, we perturbatively compute the relation between the coupling...
Dr
Benjamin Jaeger
(Swansea University)
15/07/2015, 14:40
Complex Langevin simulations provide an alternative to sample path integrals with complex weights and therefore are suited to determine the phase diagram of QCD from first principles. Adaptive step-size scaling and gauge cooling are used to make correct convergence possible. We present results for the phase diagram of QCD in the limit of heavy quarks and discuss the order of the phase...
Dr
Julien Frison
(University of Edinburgh)
15/07/2015, 14:40
The phenomenology of several problems of flavour physics require the renormalisation of four-quark effective operators at the electroweak scale. While some part of the running can be done perturbatively, it is important to perform the non-perturbative renormalisation at a scale as high as possible. We will present results at an energy range where four flavours of quarks are present, and show...
Dr
Parikshit Junnarkar
(Helmholtz Institut Mainz)
15/07/2015, 14:40
We present preliminary results from a lattice QCD calculation of the H-dibaryon using two flavours of O(a) improved Wilson fermions. We employ six-quark interpolating operators with the appropriate quantum numbers of the H-dibaryon and also explore its couplings to two-baryon channels. To improve the overlap to the ground state two smearings are employed and a generalised eigenvalue problem is...
Dr
Georg Bergner
(ITP AEC University of Bern)
15/07/2015, 15:00
In this talk I will present our newest results from the lattice
simulation of SU(2) adjoint QCD with two Dirac flavours, also known as
minimal walking technicolour. These results include the mass spectrum of the theory, in particular mesonic states with disconnected contributions and a specific spin half fermion-gluon state of the theory. I will discuss the results in comparison with SU(2)...
Mr
Rudolf Roedl
(Universität Regensburg)
15/07/2015, 15:00
We show results of generalized form factors of the nucleon from lattice simulations with Nf = 2 mass-degenerate non-perturbatively improved Wilson-Sheikholeslami-Wohlert fermions down to a pion mass of 150 MeV. We also present the resulting isovector quark angular momentum. Possible excited state contaminations are treated with correlated simultaneous fits to all 3pt functions of a given...
Mr
Ryo Yamamura
(Osaka U.)
15/07/2015, 15:00
Recently, Kaplan proposed an interesting extension of QCD : XQCD (=extended QCD) with bosonic auxiliary fields. While its partition function is kept exactly the same as that of QCD, XQCD naturally contains properties of low-energy hadrons.
We apply this extension to the two-dimensional QCD in the large N_c limit ('t Hooft model). In this solvable model, it is possible to directly examine the...
Ms
Vera Guelpers
(University of Mainz)
15/07/2015, 15:00
We study the hadronic contribution to the $\gamma$-$Z$ mixing, which determines the leading order hadronic contribution to the running of the electroweak mixing angle $\theta_W$. The required vacuum polarization function $\Pi^{\gamma Z}$ is calculated from the appropriate vector correlation functions in a mixed time-momentum representation. We explicitly calculate the connected and the...
Dr
Amy Nicholson
(UC Berkeley)
15/07/2015, 15:00
We determine scattering phase shifts for s,p,d, and f partial wave channels in two-nucleon systems using lattice QCD methods. We use a generalization of Luscher's finite volume method to determine infinite volume phase shifts from a set of finite volume ground- and excited-state energy levels on two volumes, V=(3.4 fm)^3 and V=(4.5 fm)^3. The calculations are performed in the SU(3)-flavor...
Dr
Marcus Petschlies
(HISKP, University of Bonn)
15/07/2015, 15:20
We present an update of our investigation of hadronic decays of decuplet baryons using the transfer matrix method.
In addition to the benchmark decay Delta -> pi N we look at other channels, like Sigma^{*} -> pi Sigma and Sigma^{*} -> pi Lambda
to further test the reach of the method. Lattice calculations are done using a hybrid setup with domain wall fermions on a
staggered sea at pion...
Mr
Arthur Dromard
(Goethe University Frankfurt am Main)
15/07/2015, 15:20
In lattice simulations at fine lattice spacings typical algorithms tend to freeze topologically. In such cases specific topological finite size effects have to be taken into account, to obtain physical results corresponding to infinite volume or unfixed topology. Moreover, in QCD simulations, where the volume is not that large, it is often also necessary to get rid of ordinary finite volume...
Roger Horsley
(University of Edinburgh)
15/07/2015, 15:20
Numerical lattice QCD simulations determine mass (or other) ratios
but not the scale itself, which has to be determined from experiment.
A hadron mass such as the proton mass or decay constant such as
the pion decay constant are often used for this purpose.
We discuss here the advantages of setting the scale using
a flavour-singlet quantity, which in conjunction with simulations
keeping...
Dr
Jarno Rantaharju
(CP3-Origins)
15/07/2015, 15:20
We present a study of a chirally symmetric model of four fermion interactions, the Nambu Jona-Lasinio model, on the lattice with Wilson fermions. Four fermion interactions are a necessary part of many models of beyond Standard Model physics. In particular, they can couple the Standard Model fermions to a strongly interacting Higgs sector. In technicolor models they may cause spontaneous chiral...
Dr
Jacques Bloch
(University of Regensburg)
15/07/2015, 15:40
We present our latest results on the application of the Complex Langevin method in one- and two-dimensional QCD. Although the method is stable, it unfortunately converges to an incorrect result when applied as such. After applying additional gauge cooling steps, the results agree with the known analytical results in the one-dimensional case. However, in the two-dimensional case the...
Dr
Bastian Brandt
(University of Regensburg)
15/07/2015, 15:40
We study the change of the QCD spectrum of low-lying mesons in the presence of an external magnetic field using Wilson fermions in the quenched approximation. Motivated by qualitative differences observed in the spectra of overlap and Wilson fermions for large magnetic fields, we investigate the dependence of the additive quark mass renormalisation on the magnetic field. To this purpose we...
Mingyang Sun
(University of Kentucky)
15/07/2015, 15:40
We present our calculations of the Roper state obtained from a combination of spatially large interpolation fields. The calculation is carried out with overlap valence fermion on $2 + 1$-flavor domain-wall fermion configurations on the $24^3\times 64$ lattice with $a^{-1} = 1.73\,$GeV. Our result is consistent with that from the Sequential Bayesian method (SBM) on the same lattice, and with...
Dr
Akaki Rusetsky
(HISKP, University of Bonn)
15/07/2015, 15:40
The spectrum of a bound state of three identical particles with a mass $m$ in a finite cubic box is studied within the effective field theory approach. It is shown that in the limit of a large two-body scattering length, the energy shift of a shallow bound state is given by
$\Delta E=c (\kappa^2/m) (\kappa L)^{-3/2}|A|^2 \exp(−2\kappa L/\sqrt{3})$,
where $\kappa$ is the bound-state...
Mr
Masaaki Tomii
(SOKENDAI)
15/07/2015, 16:30
We investigate correlation functions of light quark flavor non-singlet bilinear operators at short distances, where non-perturbative effects are encoded in the form of Operator Product Expansion (OPE).
Comparing lattice results and continuum perturbation theory, we determine renormalization constants and vacuum expectation values appearing in OPE. We use the lattice data obtained with the...
Mr
Oscar Akerlund
(ETH Zurich)
15/07/2015, 16:30
We study generic effects of Beyond the Standard
Model physics on the Standard Model Higgs sector. Specifically we
investigate the effects of higher order operators in the Higgs potential
in the Higgs-Yukawa and gauge-Higgs sectors separately. Our main result
is the dependence of the critical endpoint of the Electroweak
finite temperature phase transition on the scale of new physics.
Mr
Boye Buyens
(Ghent University)
15/07/2015, 16:30
We consider the matrix product state formalism for the simulation of Hamiltonian lattice gauge theories. To this end, we define matrix product states which are manifestly gauge invariant. As an application, we study 1+1 dimensional one flavor quantum electrodynamics, also known as the massive Schwinger model. First, we discuss our results on full quantum non-equilibrium dynamics induced by a...
Mr
Marco Mariti
(University of Pisa)
15/07/2015, 16:30
We report on our recent results regarding the properties of
strongly interacting matter in the presence of strong magnetic
background fields below and above the deconfinement transition.
Dr
Jonna Koponen
(University of Glasgow)
15/07/2015, 16:30
We present the first calculation of the pion electromagnetic form factor at physical light quark masses. This form factor parameterises the deviations from the behaviour of a point-like particle when a photon hits the pion. These deviations result from the internal structure of the pion and can thus be calculated in QCD. We use three sets (different lattice spacings) of n_f = 2+1+1 lattice...
katsumasa Nakayama
(Nagoya University)
15/07/2015, 16:50
We calculate the moments of charmonium current-current correlators with the Mobius domain-wall fermion. Following the method adopted by the HPQCD collaboration, we extract the charm quark mass by matching the results with the corresponding perturbative QCD calculations. We use the recently generated domain-wall fermion ensembles by the JLQCD collaboration at lattice spacings a = 0.083 fm,...
Prof.
Noriyoshi for HAL QCD Collaboration Ishii
(Research Center for Nuclear Physics, Osaka University)
15/07/2015, 16:50
Nucleaon-Nucleon interaction plays an essential role in nuclear
physics. In the same way, hyperon-hyperon interactions shold play an
important role in hyper nuclear physics. However, unlike the nucleons
who are quite stable, hyperons decay quickly so that the direct
scattering experiments are difficult. As a result, phenomenological
determination of hyperon potentials...
David Y. -J. Chu
(Department of Electrophysics, National Chaio Tung University)
15/07/2015, 16:50
We consider a chirally-invariant Higgs-Yukawa model as a limiting case of the Standard Model (SM) and investigate the model using lattice simulation. We present result of the study of the model near the mean-field using Renormalisation Group (RG) improved finite-size scalling. We derived formulae for such scaling behaviour by including the contribuations of the leading logarithms. Results for...
Dr
Debasish Banerjee
(DESY Zeuthen)
15/07/2015, 16:50
We set up a real-time path integral to study the evolution of quantum systems driven in real-time completely through the coupling of the system with the environment. This can also be interpreted as measurements being performed on the system. For a spin-1/2 system, in particular, when the measurement results are averaged over, the resulting sign problem completely disappears, and the system can...
Prof.
Shoichi Sasaki
(Tohoku University)
15/07/2015, 16:50
We discuss the effects of SU(3) symmetry breaking measured in hyperon semileptonic decays from fully dynamical lattice QCD. Our calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors of dynamical domain-wall fermions and the Iwasaki gauge action at two couplings, ¥beta$ = 2.13 and 2.25. We have estimated the value of the hyperon...
Dr
Yoshifumi Nakamura
(RIKEN AICS)
15/07/2015, 16:50
We report on preliminary results for the critical endpoint of
finite temperature phase transition of $N_f=3$ QCD at $N_t=10, 12$
and the critical endline of $N_f=2+1$ QCD at $N_t=6$
around the SU(3)-flavour symmetric point.
We employ the renormalization-group improved Iwasaki gauge action
and non-perturbatively $O(a)$-improved Wilson-clover fermion action.
Prof.
Heng-Tong DING
(Central China Normal University)
15/07/2015, 17:10
We present updated studies of chiral phase transition in Nf=2+1 and 3 QCD based on the simulations using Highly Improved Staggered Quarks on lattices with temporal extent $N_\tau$ =6 at vanishing baryon chemical potential. In Nf=2+1 QCD we have performed simulations with a strange quark fixed to its physical value and two degenerate light quarks
whose values are adjusted to have 5 values of...
Randy Lewis
(York University)
15/07/2015, 17:10
The QCD coupling appears in the perturbative expansion of the current-current two-point (vacuum polarization) function. Any lattice calculation of vacuum polarization is plagued by several competing non-perturbative effects at small momenta and by discretization errors at large momenta. We work in an intermediate region and compute vacuum polarization for many off-axis momentum directions on...
Dr
Kenji Sasaki
(CCS, University of Tsukuba)
15/07/2015, 17:10
The determination of baryon-baryon interactions directly from QCD is highly awaited. Especially for the strangeness S=-2 two-baryon system, we can investigate the SU(3) structure and its breaking effect of baryon-baryon interactions because the flavor singlet combination is allowed only in this system.
Our approach is deriving a potential from coupled channel Schroedinger equation using...
Mr
Yuya Tanizaki
(University of Tokyo)
15/07/2015, 17:10
Lefschetz-thimble method is a recently developing tool for solving the sign problem. We showed that the sign problem appearing in the mean-field approximation can be completely solved by applying this technique. The manifest reality of the physical observables is shown to be ensured in spite of the complexification of the field variables. The result is demonstrated through the heavy-quark...
Dr
Graham Moir
(Bergische Universität Wuppertal)
15/07/2015, 17:10
We study the phase diagram and mass spectrum of an $SU(2)$ Gauge-Higgs Unification scenario on a five-dimensional orbifold. This theory exhibits spontaneous symmetry breaking, and we observe that a newly discovered phase transition plays an important role in the ability of the theory to produce a standard model-like spectrum. We comment on dimensional reduction and take first steps towards...
Dr
Nodoka Yamanaka
(iTHES Group, Riken)
15/07/2015, 17:10
We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks.
Numerical simulations are carried out at single lattice spacing 0.12 fm with pion masses below 500 MeV.
We calculate both of the connected and disconnected contributions by using the all-to-all quark propagator.
We present our preliminary results for the isoscalar and...
Ms
Eliana Lambrou
(The University of Edinburgh)
15/07/2015, 17:30
The anisotropic five-dimensional SU(2) lattice gauge theory in a flat space-time background has a rich phase diagram that has been investigated extensively using various techniques. The objective is to understand whether a layered phase exists that could support a four-dimensional brane in the continuum limit, but the results to date provide no evidence for this. We present new results,...
Dr
Eigo Shintani
(Mainz University/AICS)
15/07/2015, 17:30
I present our recent analysis of isovector nucleon electromagnetic form factors, as well as the axial, scalar and tensor charges with high statistics in lattice QCD. By applying the all-mode-averaging technique to two flavors of Wilson-Clover fermions, we obtain precise lattice results of form factors at various lattice spacings and pion masses in the range 200--500 MeV for \m_{\pi}L>4. An...
Dr
Takumi Iritani
(Yukawa Institute for Theoretical Physics)
15/07/2015, 17:30
Both HAL QCD and Luscher's finite volume methods are used to calculate the
hadron interactions from lattice QCD. However, there are some systematic
deviations between these methods.
In this talk, we investigate baryon interactions from both HAL QCD and
Luscher's finite volume methods using the same lattice setups. From systematic
comparison of these two techniques, we discuss the...
Prof.
Gerrit Schierholz
(DESY)
15/07/2015, 17:30
It is argued that low energy parameters, such as the light quark masses, are related by infrared fixed points of the underlying theory. Implications for the u and d quark masses are discussed.
Prof.
Masakiyo Kitazawa
(Osaka University)
15/07/2015, 17:30
We study thermodynamics of SU(3) gauge theory on
the basis of the Yang-Mills gradient flow on fine lattices.
For this purpose, the lattice spacing of the Wilson gauge
action is determined over a wide range of $beta$ with high accuracy.
We then measure the flow time and lattice spacing dependences
of the expectation values of the energy-momentum tensor.
The extrapolation to the continuum...
Dr
Michele Brambilla
(INFN Milano Bicocca and Università di Parma)
15/07/2015, 17:50
We present an implementation of clover fermions in Numerical Stochastic Perturbation Theory. Two loop computations are already possible, e.g. we already computed critical mass. We stress that any two loop computation only relies on the known value of c_SW to one loop.
A two loop determination of c_SW would be of great interest: we report on the status of our computation of the latter.
Prof.
Kari Rummukainen
(University of Helsinki)
15/07/2015, 17:50
Future space-based gravitational wave detectors, e.g. the eLISA satellite constellation scheduled for launch in 2034, can potentially observe primordial gravitational radiation, opening a new window to the early Universe. Gravitational radiation can be generated in first order phase transitions, for example the electroweak transition in some extensions of the Standard Model. In order to...
Mr
Takaya for HAL QCD Collaboration Miyamoto
(Yukawa Institute for Theoretical Physics, Kyoto University)
15/07/2015, 17:50
Lambda_c (2286), the lightest baryon that contains
one charm quark, has been found at some experiments,
but its detailed properties such as the strength of the interaction
with the nucleon, including a possibility of forming
a deuteron-like bound state, are not known.
Due to the heavy quark symmetry, heavy baryons such as
Lambda_c (2286) sometimes show quite different behavior
from...
Dr
Oliver Baer
(Humboldt University Berlin)
15/07/2015, 17:50
The nucleon-pion-state contributions to QCD two- and three-point functions used in the calculation of the nucleon axial charge are studied in chiral perturbation theory. For sufficiently small quark masses and large volumes the nucleon-pion states are expected to have smaller total energy than the single-particle excited states. To leading order in chiral perturbation theory the results do not...
Mr
Hans-Peter Schadler
(University of Graz)
15/07/2015, 17:50
We propose to use gradient flow for the renormalization of Polyakov loops in various representations. We study Polyakov loops in 2+1 flavor QCD using HISQ action and lattices with temporal extents Nt=6,8,10 and 12 in various representations, including fundamental, sextet, adjoint, decuplet, 15-plet and 27-plet. This alternative renormalization procedure allows the renormalization over a large...
Mr
Hikaru Kawauchi
(Kanazawa University)
15/07/2015, 17:50
We apply the tensor renormalization group (TRG) method to the lattice CP(N-1) model in two dimensions. A tensor network representation of this model is derived for arbitrary N. For N=2, we compute the average energy by using the higher-order TRG. We compare it with the result of the O(3) nonlinear sigma model in two dimensions which is analyzed by the same method. Finally, we discuss the...
Prof.
Yannick Meurice
(University of Iowa)
15/07/2015, 18:10
We discuss the Tensor Renormalization Group (TRG) method for various
spin and gauge lattice models in 1+1 dimensions with emphasis
on near gapless/conformal situations. We present recent progress on optimized truncation
methods. We describe the entanglement entropy in the superfluid phase of the
O(2) model with a chemical potential.
Dr
Simon Mages
(Forschungszentrum Jülich)
15/07/2015, 18:10
We give a summary of our preliminary results on the finite temperature topological susceptibility $\chi$ from pure SU(3) theory. The simulations use a Symanzik improved action and a gluonic definition of the topological charge with cutoff effects at the $a^2$ level. We use the Wilson flow to calculate a properly renormalized topological charge and its susceptibility. Our results suggest a very...
Prof.
Shigemi Ohta
(KEK)
15/07/2015, 18:10
Current status will be reported of the nucleon isovector form factors and low moments of structure functions calculated by RBC and LHP Collaborations using a physical mass 2+1-flavor dynamical domain-wall fermion (DWF) lattice-QCD ensemble generated by UKQCD and RBC Collaborations at momentum cutoff of 1.730(4) GeV and lattice spatial extent of 5.476(12) fm.
Prof.
Kieran Holland
(University of the Pacific)
15/07/2015, 18:30
We describe a new method to determine in a stochastic fashion the Dirac
operator spectral density over the entire range of eigenvalues. This allows for example studies of the chiral limit of the fermion condensate, the mode number and the anomalous mass dimension. We apply this technique to the 2-flavor sextet SU(3) gauge theory, to investigate this theory's viability as a minimal...
Prof.
Leonardo Giusti
(University of Milano Bicocca)
15/07/2015, 18:30
We present an accurate computation of the Equation of State of SU(3)
Yang-Mills theory using shifted boundary conditions in the temporal direction. In this framework, the entropy density s(T) can be obtained in a simple way from the v.e.v. of the space-time components T_0k of
the energy-momentum tensor. Furthermore, contrary to the standard
approach, the Equation of State s(T)/T^3 can be...
Prof.
Tilo Wettig
(University of Regensburg)
15/07/2015, 18:30
We present details of our implementation of the Wuppertal
adaptive algebraic multigrid code on SIMD architectures, with
particular emphasis on the Intel Xeon Phi processor (KNC) used in
QPACE 2. As a smoother, the algorithm uses a
domain-decomposition-based solver code previously developed for
the KNC in Regensburg. We optimized the remaining parts of the
multigrid code and conclude...
Prof.
Tetsuya Takaishi
(Hiroshima University of Economics), Prof.
Yubin Liu
(Nankai University)
15/07/2015, 18:30
The hybrid Monte Carlo (HMC) algorithm has been widely used for dynamical lattice QCD simulations. One of the advantages of using the HMC algorithm is that it is a global algorithm that can update all link variables simultaneously. In this way we can greatly reduce computational cost concerning the fermionic part. We utilize this advantage for parameter estimations of the realized stochastic...
Prof.
Atsushi Nakamura
(RCNP, Osaka Univ.)
15/07/2015, 18:30
At finite density lattice QCD, the famous sign problem has prevented us from studying the QCD phase diagram based on the first-principle calculation. In order to circumvent the problem, we propose a method where we put new wine into old wineskins: i.e., we use an old idea, "canonical approach", but put into it a new ingredient, multi-precision calculations. This is free from the usual...
Ms
Aya Kagimura
(Particle Physics Theory Group, Department of Physics, Osaka university)
15/07/2015, 18:30
Around a large charge with atomic number Z > 137, the QED vacuum is expected to collapse due to the strong Coulombic force. While the relativistic quantum mechanics fails to make reliable predictions for the fate of the vacuum, the heavy ion collision experiment also does not give clear understanding of this system.
Recently,the "atomic collapse" resonances were observed on graphene where...
Mr
Hwancheol Jeong
(Seoul National University)
15/07/2015, 18:30
We calculate the strange quark condensate and the light quark condensate by using improved staggered fermions and overlap fermions, respectively. Then we report the mass dependence of the quark condensate. We use N_f = 2+1+1 MILC HISQ(highly improved staggered quark) gauge ensembles. We use a normal CG inverter to calculate the quark condensates for higher quark masses, and the Lanczos and the...
Prof.
Weonjong Lee
(Seoul National University)
15/07/2015, 18:30
We present the Standard Model evaluation of the indirect CP
violation parameter $\varepislon_K$ determined using lattice QCD
inputs: $\hat{B}_K$, $\xi_0$, $V_{us}$, and $V_{cb}$.
We find that the Standard Model prediction of $\varepsilon_K$ with
exclusive $V_{cb}$ (lattice QCD results) is lower than the experimental
value by $3.6\sigma$.
However, this tension disappears with inclusive...
Dr
Stephan Durr
(Wuppertal University / JSC Julich)
15/07/2015, 18:30
Preliminary results are presented from a new determination of f_K/f_pi which is based on a series of staggered Nf=2+1+1 simulations in the vicinity of the physical point. Special emphasis is put on the interpolation to the physical point, the finite-volume corrections, the continuum extrapolation and the breaking of the isospin symmetry.
Richard Woloshyn
(TRIUMF)
15/07/2015, 18:30
Free-form smearing was designed as a way to implement source
operators of any desired shape. A variation of the method is introduced
that reduces the computational cost by reducing the number of link
multiplications to its absolute minimum. Practical utility is
demonstrated through calculations of bottomonium and B meson masses.
Yusuke Yoshimura
(RIKEN Advanced Institute for Computational Science)
15/07/2015, 18:30
In numerical calculation of the lattice QCD, the sign problem of Monte Carlo methods has been a major issue.
A numerical renormalization group called tensor renormalization group (TRG) is one of the candidates for the solution of this problem.
Grassmann tensor renormalization group (GTRG) is a generalization of the TRG to fermion systems.
In this study, We apply the GTRG to the lattice...
Dr
Azusa Yamaguchi
(University of Edinburgh)
15/07/2015, 18:30
We discuss progress and performance from the development of the Grid
data parallel interface for cartesian fields of tensor data types. The
library is suitable for the simulation of QCD including multiple grids.
Wherever appropriate the interface is quite similar to that of QDP++,
but the library makes use of C++11 features to reduce the volume of code,
compared to QDP++ while...
Mr
JAEHOON LEEM
(Seoul National University)
15/07/2015, 18:30
We improve heavy-heavy currents for calculating B ̅ →D^((*) ) lν ̅ semi-leptonic form factors with Oktay-Kronfeld (OK) heavy quarks. The OK action, which has dimension 6 and 7 interaction terms, can control the discretization errors of heavy quarks (b and c quarks). The OK action is improved through third order in HQET power counting. We report work on heavy-heavy currents to get the...
Mr
Marco garofalo
(The University of Edinburgh)
15/07/2015, 18:30
L\"uscher recently introduced Instantaneous Stochastic Perturbation Theory (ISPT) as a method for the stochastic evaluation of lattice perturbation theory. We present an exploratory study of its properties in $\phi^4$ theory, and we compare it with both analytical computations and Numerical Stochastic Perturbation Theory. In addition, we propose a automated method based on ISPT for solution of...
Dr
Craig McNeile
(Plymouth University)
15/07/2015, 18:30
Preliminary results for the effect of open boundary conditions on the masses of glueballs and the probability distributions of glueball correlators, in quenched QCD, are presented. Initial results from glueball correlators computed on unquenched ensembles downloaded from the ILDG data grid are reported.
Prof.
Gernot Münster
(University of Münster)
15/07/2015, 18:30
We present the expansions of the masses of the pseudoscalar mesons in chiral perturbation theory at next-to-leading order for twisted mass lattice QCD with three light quark flavours, taking the mass difference between the up and down quarks into account.
Dr
Shinji Motoki
(High Energy Accelerator Research Organization(KEK))
15/07/2015, 18:30
We are developing a code set "Bridge++" for simulations of lattice gauge theories that aims at an extensible, readable, and portable workbench, while achieving high performance.
This work concerns the design of Bridge++ to incorporate the accelerator devices, such as GPUs.
As generic frameworks for heterogeneous programming using CPU and accelerator devices, we apply OpenCL and OpenACC to...
Mr
Masayuki Wakayama
(Nagoya University)
15/07/2015, 18:30
We study the possible significance of four-quark states in the isosinglet scalar mesons ($J^{PC}=0^{++}$, I=0) by performing two-flavor full lattice QCD simulations on an $8^3 ¥times 16$ lattice using the improved gauge action and the clover-improved Wilson quark action. In particular, we evaluate the propagators of molecular and tetraquark operators together with singly disconnected diagrams....
Mr
Ken-Ichi Ishikawa
(Hiroshima University, Department of Physical Science)
15/07/2015, 18:30
We present the quark mass and axial current renormalization factors for the RG-improved gauge and
the stout smeared $O(a)$-improved Wilson quark actions.
The $O(a)$ improvement coefficient for the three-flavors of dynamical quarks has been determined previously with the stout-link
smearing parameter $\alpha=0.1, n=6$.
We employ the Schr\"{o}dinger functional scheme and obtain the...
Mr
Joni Suorsa
(University of Helsinki, Helsinki Institute of Physics)
15/07/2015, 18:30
SU2 with Nf=8 is believed to have an infrared conformal fixed point. We use the spectral density method to evaluate the coupling constant dependence of the mass anomalous dimension. We use massless theory with Schrödinger functional boundary conditions and HEX smeared Wilson clover fermions.
Prof.
Takehiro Azuma
(Setsunan University)
15/07/2015, 18:30
The IIB matrix model has been proposed as a nonperturbative definition of superstring theory. In this work, we study the Euclidean version of this model in which extra dimensions can be dynamically compactified if a scenario of the spontaneous breakdown of the SO(10) rotational symmetry is realized. Monte Carlo calculations of the Euclidean IIB matrix model suffer from a very strong complex...
Mr
Daniel Richtmann
(University of Regensburg)
15/07/2015, 18:30
The setup cost of a modern solver such as the DD-$\alpha$AMG (Wuppertal Multigrid) is a significant contribution to the total time spent on solving the Dirac equation, and in HMC it can even be dominant. We present an improved implementation of this algorithm with modified computation order in the setup procedure. By processing multiple right-hand sides simultaneously we can alleviate many of...
Dr
jangho Kim
(Korea Institute of Science and Technology Information)
15/07/2015, 18:30
We present the preliminary results of the wave function renormalization factor Z_q and mass renormalization factor Z_m from the bilinear operators obtained using non-perturbative renormalization method(NPR) in the RI-MOM scheme with improved staggered fermions.
We use fine ensembles of MILC asqtad lattices (N_f=2+1) with 28^3 \times 96 geometry and am_\ell / am_s = 0.0062 / 0.031.
We also...
Dr
Nigel Cundy
(Seoul National University)
15/07/2015, 18:30
We report on our efforts to impliment overlap fermions on NVIDIA GPUs using CUDA, commenting on the algorithms used, implemetation details, and the performance of our code.
Mr
Jeonghwan Pak
(Seoul National University)
15/07/2015, 18:30
Matching factors for the four-fermion operators relevant to B_K are obtained using the Non-Perturbative Renormalization(NPR) method in the RI-MOM scheme. Our NPR codes are calculated in Double Precision(DP) and optimized on Fermi GPU. NVIDIA released The GTX Titan X based on the Maxwell architecture. The Single Precision(SP) calculation performance of the GTX Titan X is improved, but the ratio...
Dr
Andreas Juettner
(University of Southampton)
15/07/2015, 18:30
With the aim of studying the relevance and properties of critical slowing down in Monte Carlo simulations of lattice quantum field theories we carried out a high precision numerical study of the discretised two-dimensional CP^{N-1} model at N=10 using an over-heat bath algorithm. We identify critical slowing down in terms of slowly-evolving topological modes and present evidence that other...
Prof.
Wolfgang Bietenholz
(Universidad Nacional Autonoma de Mexico)
15/07/2015, 18:30
The 2d CP(N-1) models share a number of features with QCD,
like asymptotic freedom, a dynamically generated mass gap,
and topological sectors. They have been formulated and analysed
successfully in the formalism of the so-called D-theory.
In that framework, we propose an experimental set-up for
the quantum simulation of the CP(2) model. It is based on
ultracold alkaline-earth-atoms...
Prof.
Ming Gong
(Institute of High Energy Physics, CAS)
15/07/2015, 18:30
We report a quark spin calculation from the anomalous Ward identity with overlap fermions on 2+1 flavor dynamical fermion configurations. Such a formulation decomposes the divergence of the flavor-singlet axial-vector current into a quark pseudoscalar term and a triangle anomaly term, flavor by flavor. We use the overlap fermion for the valence and the quark loop so that the renormalization...
Yasumichi Aoki
(KMI, Nagoya University)
15/07/2015, 18:30
SU(3) gauge theory with eight massless fundamental fermions seems to be near the conformal boundary, and is a candidate of walking technicolor. Along the series of study by LatKMI collaboration using HISQ fermions, S-parameter and vector decay constant, which provide important constraints in the model building, are calculated for this theory. Use of various volumes allows a systematic...
Prof.
Shoji Hashimoto
(KEK)
15/07/2015, 18:30
We calculate the spectral function of the QCD Dirac operator using the four-dimensional effective operator constructed from the Mobius domain-wall implementation. We utilize the eigenvalue filtering technique combined with the stochastic estimate of the mode number. The spectrum in the entire eigenvalue range is obtained with a single set of measurements. Results on 2+1-flavor ensembles with...
Mr
Marcin Szyniszewski
(Lancaster University)
15/07/2015, 18:30
We employ a strong coupling expansion - similar to the one used in the lattice field theory studies [1] - to solve the one-dimensional extended t-V model of fermions on a lattice [2]. This model is solved for a range of filling factors, including both commensurate - where a charge density wave is present - and incommensurate densities. The first set consists not only of a trivial case of half...
Dr
Hideo Matsufuru
(High Energy Accelerator Research Organization (KEK))
15/07/2015, 18:30
We study the SU(2) gauge theory with dynamical domain-wall
fermions in fundamental and adjoint representations.
Dynamical simulations with fundamental fermions are performed
with numbers of flavors Nf=2,4,6, and 8. Nf dependence of
the meson masses and decay constants are investigated.
The same analyses are applied also to the adjoint fermions,
based on the investigation of the Aoki...
Mr
Thomas Kloiber
(University of Graz)
15/07/2015, 18:30
We study the two dimensional nonlinear O(3) model with a chemical potential coupled to the conserved charge. The complex action problem occurring at nonzero chemical potential is solved by means of a duality transform, which yields real and positive weights and makes Monte Carlo simulations feasible. We find a phase transition at the end of a Silver Blaze region, where a net number of...
Ms
Yuko Murakami
(Hiroshima University)
15/07/2015, 18:30
Last year we reported the property of the the Moebius Domain Wall Fermions (MDWF) in the Schroedinger Functional (SF) scheme with the palindromic fifth dimensional parameters and the appropriate boundary operator at the tree-level, and the non-universal behavior for a small fifth direction extent $N_5$.
We find that this behavior comes from the residual mass at the tree-level and the...
Mr
Markus Werner
(University of Bonn)
15/07/2015, 18:30
We present first results for I=1 pipi scattering with N_f=2+1+1 twisted mass fermions utilizing the sLapH method. The rho mass and decay width are computed for various pion masses and lattice spacings. Special care was taken in the analysis of systematic uncertainties.
Dr
Miho Koma
(Nihon University, College of International Relations)
15/07/2015, 18:30
We study the static three-quark potential in SU(3) lattice gauge theory at zero
temperature with the Polyakov loop correlation function consisting of three Polyakov loops.
By employing the multi-level algorithm we overcome the smallness of the signal to noise ratio and obtain remarkably clean signals.
We extend our previous investigation of the three-quark potential and
compute the...
Dr
Anna Hasenfratz
(University of Colorado)
15/07/2015, 18:30
We investigate the discrete $\beta$ function of the 2-flavor SU(3) sextet model using the gradient flow scheme. Staggered fermion investigations suggest that the system is chirally broken, contradicting earlier Schroedinger functional Wilson fermion studies that were consistent with conformality. Our results, using improved Wilson fermions and the gradient flow RG scheme, suggests a step...
Vanessa Koch
(Trinity College Dublin)
15/07/2015, 18:30
We investigate the use of stochastically estimated light quark propagators in correlation functions involving a static color source. To this end we compute the static-light meson correlation function in the stochastic LapH framework, using N_f= 2+1 gauge configurations generated through the CLS effort. Together with the static potential, we obtain an estimate for the expected string breaking distance.
Dr
Takashi Umeda
(Hiroshima University)
15/07/2015, 18:30
We study the $N_f=2+1$ QCD at nonzero temperatures using nonperbatively improved Wilson quarks of the physical masses by the fixed scale approach. We perform physical point simulations at finite temperatures with the coupling parameters which were adopted by the PACS-CS collaboration in their studies using the reweighting technique. Zero temperature values are obtained on the PACS-CS...
Mr
Yong-Chull Jang
(Seoul National University)
15/07/2015, 18:30
We present updated results of the heavy-meson spectrum obtained using the Oktay--Kronfeld (OK) action on MILC asqtad lattices. The OK action was designed to improve the heavy-quark action of the Fermilab formulation by including complete dimension six and part of dimension seven bilinear improvement terms. Improvement terms are truncated by power counting of order $\Lambda^3/m^3$ for...
Dr
Ross Young
(University of Adelaide)
16/07/2015, 08:30
By considering an appropriate modification of the action, the Feynman–Hellman (FH) theorem provides an alternative technique for studying hadron matrix elements. We report on new developments in the extension of the FH technique to the study of non-forward matrix elements, where preliminary results demonstrate the feasibility of accessing relatively large momentum transfers. In the near...
Mr
Venkit Ayyar
(Duke University)
16/07/2015, 08:30
We study two flavors of massless staggered fermions interacting via an on-site four-
fermion interaction and argue that the model contains an exotic quantum critical point
separating the perturbative massless phase from a massive fermion phase at strong cou-
plings where the fermion bilinear condensate remains zero. We believe that no spontaneous
symmetry breaking occurs at the transition....
Tomomi Ishikawa
(RIKEN BNL Research Center)
16/07/2015, 08:30
Neutral B meson mixing matrix elements and B meson decay constants are calculated in the infinite b quark mass limit. For the light quarks, domain-wall fermion (DWF) formalism is employed. The calculations are carried out using all-mode-averaging (AMA) technique on Nf=2+1 dynamical DWF ensembles with lattice spacings of nearly 0.08fm and 0.11fm, where pion masses are relatively heavy...
Prof.
Yusuke Taniguchi
(University of Tsukuba)
16/07/2015, 08:30
The canonical partition function is related to the grand canonical one
through the fugacity expansion.
In this talk we perform the fugacity expansion by a method of the
hopping parameter expansion in temporal direction.
The canonical partition function is evaluated for Nf=2 QCD upto
baryon numbers of nB=30 in a wide range of temperature.
After derivation of the canonical partition...
Dr
Vincent Drach
(CP3 Origins - University of Southern Denmark)
16/07/2015, 08:30
We present a non perturbative study of SU(2) gauge theory with two
fundamental Dirac flavours. We discuss how the model can be used as a
template for composite Dark Matter (DM). We estimate two types of
interactions of the DM candidate with the Standard Model : the interaction
through Higgs exchange and the interaction through photon exchange computing the electric polarizability of the DM...
Dr
Padmanath Madanagopalan
(University of Graz)
16/07/2015, 08:30
I will discuss recent lattice study of charmonium-like mesons with
$J^{PC}=1^{++}$ and three quark contents $\bar cc\bar du$,
$\bar cc(\bar uu + \bar dd)$ and $\bar cc\bar ss$, where the latter
two can mix with $\bar cc$. In this quantum channel, the long known
exotic candidate, X(3872), resides. This simulation employs $N_f=2$,
$m_\pi=266~$MeV and a large basis of $\bar cc$,...
Prof.
Carleton DeTar
(University of Utah)
16/07/2015, 08:50
We present preliminary, high-precision results for the decay constants
$f_B$ and $f_{B_s}$ from simulations with HISQ heavy and light valence
and sea quarks. Calculations are carried out with several heavy
valence-quark masses on ensembles with 2+1+1 flavors of HISQ sea
quarks at five lattice spacings and three light sea quark mass ratios
$m_{ud}/m_s$, including approximately physical...
Prof.
Shinsuke Nishigaki
(Shimane University)
16/07/2015, 08:50
Based on the exact relationship to random matrix theory, we present alternative methods of evaluating the probability distribution of the k-th smallest Dirac eigenvalue in the epsilon regime of QCD and related gauge theories. By employing (1) the Nystrom-type evaluation of Fredholm determinants and Pfaffians and/or (2) the interrelationship between tau functions for random matrix ensembles at...
Mr
Shotaro Oka
(Rikkyo Univ.)
16/07/2015, 08:50
The canonical approach is one of the methods that have been pursued to solve the sign problem. However, this approach has the numerical instability, and most people have thought that this approach does not work for a long time.
We found that this instability can be solved by using the multiple precision computation. In this talk, we will study effects of the multiple precision computation...
Dr
Krzysztof Kutak
(Instytut Fizyki Jadrowej Polskiej Akademii Nauk)
16/07/2015, 08:50
In the talk I will overview status of QCD at region of phase space when the partons form a dens system leading eventually to parton saturation i.e. situation when the partons are not growing any more due to nonlinear dynamics.
I will overview recent developments leading to construction of gluon densities which take into account saturation effects. Finally I will present predictions for...
Dr
Krzysztof Cichy
(Goethe University Frankfurt)
16/07/2015, 08:50
We present results from an on-going computation of masses of D mesons, D_s mesons and charmonium, including both ground states and several parity and angular momentum excitations. We employ 2+1+1 flavours of dynamical maximally twisted mass fermions at three lattice spacings and three u/d quark masses at each lattice spacing. We consider different combinations of valence quarks, with either...
Dr
Enrico Rinaldi
(Lawrence Livermore National Laboratory)
16/07/2015, 08:50
The Stealth Dark Matter model contains a candidate composite dark matter particle which appears as a bosonic neutral baryon of a new strongly coupled sector. The elementary constituents of this composite state carry electroweak charges. This construction provides a mechanism to naturally reduce the strength of dark matter interactions with standard model particles. However such interactions...
Dr
Thomas Rae
(University of Wuppertal)
16/07/2015, 09:10
We present a preliminary study of the charmed meson spectra using the electrically neutral subset of the new Budapest-Marseille-Wuppertal $N_f=2+1+1$ gauge configurations that utilise the 3-HEX smeared clover action. The analysis is performed with a focus on the hyperfine splitting.
Dr
Evan Berkowitz
(Lawrence Livermore National Laboratory)
16/07/2015, 09:10
The Strong CP Problem can be resolved by introducing an additional global symmetry known as Peccei-Quinn symmetry.
Once PQ symmetry is broken the associated particle, the QCD axion, is a plausible dark matter candidate.
Calculating the cosmological energy density of the axion requires nonperturbative QCD input---the high-temperature topological susceptibility.
I will show results from a...
Dr
James Simone
(Fermilab)
16/07/2015, 09:10
We compute hadronic matrix elements for neutral $B$-meson mixing in
the Standard Model and beyond as well as the corresponding operators
for the the short-distance contribution to $D$-meson mixing. On the
same sets of gauge ensembles, we calculate the leptonic decay
constants for the $B$- and $D$-meson systems. The matrix elements are
computed with asqtad light quarks and clover heavy...
Mr
Lukas Varnhorst
(Wuppertal University)
16/07/2015, 09:10
The nucleon-sigma-terms are measures of the light-quark- and strange-quark-content of the nucleon. Especially the stangeness-content is of significant interest for dark-matter searches, as it determines the coupling of several dark matter candidates to hadronic matter. While the sigma-terms can not be measured directly they can be determined via lattice QCD from first principles.
The...
Dr
Savvas Zafeiropoulos
(Goethe University Frankfurt)
16/07/2015, 09:10
We present the comparison of the analytical microscopic spectral density for lattice QCD with $N_f=2$ twisted mass fermions with the one obtained on the lattice utilizing configurations produced by the ETM collaboration.
We extract estimates for the chiral condensate as well as the low-energy constant $W_8$ of Wilson $\chi$-PT by employing spectral information of the Wilson Dirac operator...
Mr
Ryutaro Fukuda
(The University of Tokyo / ETH Zurich)
16/07/2015, 09:10
We calculate the baryon chemical potential (μ) dependence of thermodynamic observables, i.e., pressure, baryon number density and susceptibility by lattice QCD using the canonical approach with winding number expansion.We compare the results with those obtained by the multi parameter reweighting (MPR) method; Both methods give very consistent values in the regions where errors of the MPR are...
Dr
Christian Torrero
(on behalf of the Budapest-Marseille-Wuppertal Collaboration (Centre de Physique Théorique and CNRS, Aix-Marseille Université, France))
16/07/2015, 09:30
After a detailed analysis of possible sources of systematic uncertainty, ab-initio $N_f=2+1$ results for the up-down and strange quark content - with pion masses all the way down to the physical point - will be presented and discussed.
Andrea Shindler
(Forschungszentrum Jülich)
16/07/2015, 09:30
The nucleon EDM receives potential contributions from fermionic and gluonic local operators representing the effective interactions from BSM physics.
We have recently proposed to use the gradient flow to calculate the QCD component of these key BSM matrix elements. I present an update of the results we have obtained.
Mr
Asobu Suzuki
(University of Tsukuba)
16/07/2015, 09:30
High-order cumulants are numbers characterizing the probability distribution and have a lot of physical information.
However, sign problem makes it difficult to numerical calculation of high-order cumulants in finite density lattice QCD.
In this study we realize the calculation of high-order cumulants with "canonical ensemble method" in heavy quark region.
Also, we study a finite density...
Prof.
Jacobus Verbaarschot
(Stony Brook University)
16/07/2015, 09:30
The behavior of quenched Dirac spectra of two-dimensional lattice QCD is
consistent with spontaneous chiral symmetry breaking which is forbidden
according to the Coleman-Mermin-Wagner theorem. One possible resolution of this
paradox is that because of the bosonic determinant that enters in the
partially quenched partition function the conditions of this theorem
are violated allowing...
Ms
Antje Peters
(Goethe-Universität Frankfurt am Main)
16/07/2015, 09:30
We explore the possible existence of qq-anti-b-anti-b tetraquark
states, where qq denotes two up/down, strange or charm quarks. To this end we compute potentials of two static antiquarks in the presence of the two quarks qq of finite mass using lattice QCD. Then we check, whether these potentials are sufficiently attractive to host bound states. We find strong indication for a bound...
Philippe de Forcrand
(ETH Zurich & CERN)
16/07/2015, 09:50
We discuss properties of actions which are invariant under
smooth deformations of the lattice fields, which are
restricted to a subspace of phase space. In particular
we comment on the continuum limit of such
actions and show how to directly measure the free energy.
We also investigate possible applications to finite
density systems.
Dr
Andrei Alexandru
(The George Washington University)
16/07/2015, 09:50
In the presence of a constant electric field the vacuum becomes
unstable due to Schwinger pair creation. One way to avoid this
instability is to use Dirichlet boundary conditions. In this
case the chiral condensate vanishes on the walls and it is important
to know how quickly it gets restored to its bulk value. A
sigma-model calculation predicts that the region where the
condensate...
Mr
Joshua Berlin
(University of Frankfurt)
16/07/2015, 09:50
The conjecture that several recently observed mesons have a structure, which is not dominated by an ordinary quark antiquark pair, but by a four-quark structure, is being actively investigated both theoretical and experimentally. Such a state maybe characterised as molecular state or as a diquark-antidiquark pair. Lattice QCD provides a theoretically sound framework to study such states. In...
Dr
Tanmoy Bhattacharya
(Los Alamos National Laboratory)
16/07/2015, 09:50
The presentation will discuss the connection between RI-SMOM and MSbar schemes for the quark chromo EDM operators. A preliminary study of the signal in the matrix element of neutron EDM using clover quarks on an HISQ ensemble will also be described.
Dr
Brian Colquhoun
(University of Glasgow)
16/07/2015, 09:50
Lattice NRQCD is a relatively inexpensive formalism that can be used to simulate b quarks on the lattice at their physical mass. The HPQCD collaboration has used radiatively-improved NRQCD for b quarks in bottomonium to determine the decay rate to leptons of the ground-sate Upsilon and its first radial excitation in lattice QCD. Using time moments of vector bottomonium current-current...
Dr
yibo Yang
(University of kentucky)
16/07/2015, 09:50
We calculate glue spin with the overlap fermion on 2+1 flavor domain wall fermion configurations as a function of the nucleon momentum. The calculation is carried out on 24^3 x 64 and 32^3 x 64 lattice at two lattice spacings and the light sea quarks correspond to pion mass at 330 MeV and 290 MeV on these two lattices. Other issues related to the proton spin will be discussed.
Mr
Matthias Rottmann
(University of Wuppertal)
16/07/2015, 10:40
In this talk, we present a multigrid based eigensolver for computing low modes of the hermitian Wilson Dirac operator. For the non-hermitian case, multigrid methods have already replaced conventional Krylov subspace solvers in many lattice QCD computations. Since the gamma5 preserving aggregation based interpolation is valid for both, the hermitian and the non-hermitian case, inversions of...
Mr
Justus Tobias Tsang
(University of Southampton, UK)
16/07/2015, 10:40
This talk will provide an overview of RBC/UKQCD's charm project on their 2+1 flavour physical point ensembles using Moebius Domain Wall Fermions for the light as well as for the charm quark. I will discuss the analysis strategy and present first preliminary results for D and D_s decay constants.
Helvio Vairinhos
(ETH Zurich)
16/07/2015, 10:40
The diagrammatic Monte Carlo method has been a very fruitful tool for taming, and in some cases even solving, the sign problem in several lattice models. We have recently proposed a diagrammatic model for simulating lattice gauge theories with staggered fermions at arbitrary coupling, which extends earlier successful efforts to simulate lattice QCD at finite baryon density in the...
Mr
David Murphy
(Columbia University)
16/07/2015, 10:40
We have performed global fits of $f_\pi$ and $m_\pi$, from a variety of RBC-UKQCD domain wall fermion ensembles, to $SU(2)$ partially quenched chiral perturbation theory at NNLO. We report values for 9 NLO and 8 linearly independent combinations of NNLO partially quenched low energy constants, which we compare to other lattice and phenomenological determinations. We discuss the convergence of...
Dr
Rajan Gupta
(Los Alamos National Lab)
16/07/2015, 10:40
Results for the matrix elements of quark bilinear operators within a nucleon state will be presented using nine ensembles of gauge
configurations generated by the MILC collaboration using the HISQ
action with 2+1+1 dynamical flavors. Excited state contamination and extrapolation to the physical point will be discussed for the charges g_A, g_S and g_T, the vector and axial form factors, and...
Mr
Christian Zielinski
(Nanyang Technological University)
16/07/2015, 10:40
The 4 flavors of the usual staggered fermion give rise to 16 pions (pseudoscalar mesons). We study the effect on the pion spectrum of turning on the 2-flavor staggered Wilson term in the staggered fermion action. 8 of the pions become heavy while 8 remain light. 6 of the light pions are identified as two copies of the 2-flavor pion triplet. They have the same light quark content but different...
Mr
Tobias Rindlisbacher
(ETH Zurich)
16/07/2015, 11:00
We present a flux representation based lattice formulation of the partition function corresponding to the SU(2)-chiral Lagrangian, including a chemical potential and scalar/pseudo-scalar source terms. Lattice simulations are then used to obtain non-perturbative properties of the theory, in particular its mass spectrum at zero and non-zero pion density.
Mr
Jakob Simeth
(University of Regensburg)
16/07/2015, 11:00
Disconnected contributions to hadronic quantities are noisy and still computationally challenging. Here, we explore the possibilities of Multigrid-based eigensolvers for Low-mode averaging and related methods.
Using only the few lowest approximate eigenmodes of the Hermitian Dirac operator $\gamma_5 M$ allows us to avoid expensive exact solves and improve the signal efficiently.
In this...
Ms
Ava Khamseh
(Edinburgh University)
16/07/2015, 11:00
We will report on the RBC/UKQCD charm project with (2+1)-flavor Domain Wall fermions at the physical point, and present progress on the determination of the matrix element of the VV+AA operator, and the Bag and Xi-parameters in the region of the physical charm quark mass. We will address the region of practical use of the domain wall action for heavy quark simulation and outline a strategy for...
Robert Mawhinney
(Columbia University)
16/07/2015, 11:00
We have performed global fits of pseudoscalar masses and decay constants,
from a variety of RBC-UKQCD domain wall fermion ensembles, to $SU(3)$
partially quenched chiral perturbation theory at NNLO. We report
values for 9 NLO and 10 linearly independent combinations of NNLO
partially quenched low energy constants, which we compare to other
lattice and phenomenological determinations. We...
Dr
Andreas Athenodorou
(University of Cyprus)
16/07/2015, 11:00
We extract the neutron electric dipole moment (nEDM) |d_n| on configurations produced with N_f=2+1+1 twisted mass
fermions with lattice spacing of a=0.082fm and a light quark mass that corresponds to M_{\pi}=370 MeV. We do so by
evaluating the CP-odd form factor F_3 for small values of the vacuum angle \theta at the limit of zero momentum
transfer. This limit is taken using a...
Dr
Agostino Patella
(CERN and Plymouth University)
16/07/2015, 11:20
In order to calculate QED corrections to hadronic quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss' law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field...
Mr
Takashi Suzuki
(Osaka university)
16/07/2015, 11:20
We report on our study of D meson semileptonic decays in QCD
with 2+1 flavors of the Moebius domain-wall fermions.
Gauge ensembles are generated at lattice cut-off around 2.4 GeV
and pion masses as low as 300 MeV. Relevant form factors are
calculated by using the Moebius action also for charm quarks.
Dr
Hiroya Suno
(RIKEN Advanced Institute for Computational Science; RIKEN Nishina Center)
16/07/2015, 11:20
We are developing a computer code for calculating eigenvalues of the non-Hermitian O(a)-improved Wilson-Dirac operator. We introduce here the Sakurai-Sugiura method, which is an eigensolver algorithm based on a contour integral, allowing us to calculate desired eigenvalues located inside a given contour. We report the test results for low-lying eigenvalues obtained with free-case, quenched and...
Dr
Markus Pak
(University of Graz)
16/07/2015, 11:20
Recently, a new $SU(4)$ symmetry has been established, which appears after removing the quasi-zero modes from the Overlap Dirac operator. Namely, the $\rho, \rho', \omega, \omega', a_1, b_1$ and possibly $f_1$ $J=1$ mesons become mass degenerate after the quasi-zero mode removal. The $SU(4)$ symmetry contains $SU(2)_L \times SU(2)_R \times U(1)_A$ as a subgroup and predicts, among other...
Owe Philipsen
(Goethe-University Frankfurt)
16/07/2015, 11:20
A three-dimensional effective lattice theory of Polyakov loops
can be construted by integrating over the spatial links in combined
strong coupling and hopping parameter expansions. The effective theory
is valid for sufficiently heavy quarks and coarse to intermediate lattice
spacings. In its domain of validity, the sign problem is weak enough to
enable simulations at finite baryon...
247.
Neutron-antineutron oscillation matrix elements with domain wall fermions at the physical point
Dr
Sergey Syritsyn
(RIKEN BNL Research Center)
16/07/2015, 11:20
Neutron-antineutron oscillations are hypothetical processes changing the baryon number by 2 units. Compared to proton decay, they present another scenario of baryon number violation and, if found, they would have different implications for phenomenology of baryogenesis. If such baryon number violation exists at higher scales beyond the Standard model, it will manifest itself at the hadron...
Dr
Alexei Strelchenko
(FNAL)
16/07/2015, 11:40
We present a brief overview of deflation algorithms recently implemented in the SciDAC QUDA library
for solving the lattice-Dirac equation with multiple right-hand sides on NVIDIA accelerators.
In particular, we discuss implementation aspects of the mixed precision technique for the eigenvalue deflation which
helps to considerably relax GPU memory requirements while allowing for an...
Mr
Jonas Rylund Glesaaen
(Goethe University Frankfurt)
16/07/2015, 11:40
We discuss the fermionic contribution to a three dimensional effective lattice theory for heavy quarks. We first study the mathematical structure of higher order contributions of the hopping parameter expansion to the effective action. We then examine how to apply a graphical linked cluster expansion to retrieve analytical results for various lattice quantities such as nucleon number and...
Dr
Nazario Tantalo
(Rome University and INFN "Tor Vergata")
16/07/2015, 11:40
In order to calculate QED corrections to hadronic quantities by means of lattice simulations, a coherent description of electrically-charged states in finite volume is needed. In the usual periodic setup, Gauss' law and large gauge transformations forbid the propagation of electrically-charged states. A possible solution to this problem, which does not violate the axioms of local quantum field...
Dr
Thomas Primer
(University of Arizona)
16/07/2015, 11:40
We present a calculation of the $D\to\K,l,\nu$ and $D\to\pi,l,\nu$ semileptonic form factors at $q^2=0$.
These form factors are needed for the determination of the CKM matrix elements $\lvert{V_{cs}}\rvert$ and
$\lvert{V_{cd}}\rvert$ respectively.
This work uses the HISQ action for both valence quarks and sea quarks on MILC $N_f=2+1+1$ configurations, with ensembles including several at the...
Mr
Utku Can
(Tokyo Institute of Technology)
16/07/2015, 11:40
The electromagnetic form factors of the spin-3/2 $\Omega$ baryons, namely the $\Omega$, $\Omega_c^\ast$, $\Omega_{cc}^\ast$ and $\Omega_{ccc}$, are calculated in full QCD on $32^3$ x 64 PACS-CS lattices with a pion mass of 156(9) MeV. The electric charge radii and magnetic moments from the E0 and M1 multipole form factors are extracted. Results for the electric quadrupole form factor, E2, are...
Dr
Konstantin Ottnad
(University of Bonn)
16/07/2015, 11:40
We employ lattice techniques to compute both sides of the Witten-Veneziano formula.
For the one side we perform dedicated quenched simulations
and use the spectral projector method to determine the topological
susceptibility in pure Yang-Mills theory. The other side we determine
in lattice QCD with $N_f=2+1+1$ dynamical Wilson twisted mass fermions
including for the first time also the...
Prof.
Mithat Unsal
(North Carolina State University)
17/07/2015, 09:00
Resurgent trans-series provide a novel mathematical formalism to unify perturbative and non-perturbative physics, leading to new insights into the general structure of quantum theories. I will review the main ideas with some illustrative examples.
In many quantum mechanical systems, all orders non-perturbative data is encoded into perturbation theory, and it can be decoded. In QFTs, there...
Prof.
Francesco Sannino
(CP3-Origins & DIAS, University of Southern Denmark)
17/07/2015, 09:45
Circa 95% of the universe is made of unknown forms of matter and energy, while to describe the remaining 5% one needs at least three fundamental forces, i.e. Quantum Electrodynamics, Weak Interactions and Quantum Chromo Dynamics (QCD). Furthermore strong interactions are responsible for creating the bulk of the bright mass, i.e. the 5%. It is therefore natural to expect that to correctly...
Prof.
Toru Iijima
(KMI, Nagoya University)
17/07/2015, 11:00
Talk
In this talk, we discuss the status and future prospect in B physics, focusing on the SuperKEKB/Belle II experiment at KEK, with the target peak luminosity of 8 \times 10^35 cm^-2s^-1. This enables us to study decays of heavy flavor particles, B and D mesons as well as \tau leptons, at the order of O(10^10) per year, and to search for New Physics through processes sensitive to presence of...
Prof.
Carlos Pena
(Universidad Autónoma de Madrid and IFT-UAM/CSIC)
17/07/2015, 11:45
I will review recent progress in lattice computations relevant for B- and charm physics. Emphasis will be put on the interplay with the upcoming new generation of experimental results.
Dr
Alberto Ramos
(CERN)
17/07/2015, 14:00
We will use the idea of twisted reduction and volume independence to numerically investigate the large N limit of Yang-Mills theories by reducing two of the directions to a single point. We will show that this framework might be convenient to analyze some properties of these theories.
Dr
Masayasu Hasegawa
(Joint Institute for Nuclear Research)
17/07/2015, 14:00
The purpose of this study is to show that monopoles are related to chiral symmetry breaking and to instantons, using the Overlap fermions as an analytical tool.
In order to study these relations, we add one pair of monopoles with different magnetic charges to the quenched SU(3) configurations by a monopole creation operator. We then count the number of zero modes, and compute the average...
Arata Yamamoto
(The University of Tokyo)
17/07/2015, 14:00
The complex Langevin method is one hopeful candidate to tackle the sign problem.
This method is applicable not only to QCD but also to nonrelativistic field theory.
We present the simulation results of nonrelativistic condensed matter systems.
Dr
Lorenzo Riggio
(INFN Roma Tre)
17/07/2015, 14:00
We present lattice results for the form factors relevant for K -> pi l nu decays, obtained from simulations performed by the European Twisted Mass Collaboration with Nf=2+1+1 flavors of dynamical quarks, at three values of the lattice spacing and pion masses as low as 250 MeV.
Our determination of f_+(0), which in combination with the experimental result for (f_+(0)*V_us) can be used to...
Prof.
Seyong Kim
(Sejong University)
17/07/2015, 14:00
To study the in-medium modification of quarkonium properties, charmonium correlators at $140.4 (\beta =6.664) \le T \le 221 (\beta = 7.280)$ (MeV) are calculated using the NRQCD formalism on $48^3 \times 12$ gauge configurations with dynamical $N_f = 2 + 1$ flavors of Highly Improved Staggered Quarks (HISQ). To determine the "zero energy shift" for these lattices, we perform a fine zero...
Dr
Hiroshi Ohno
(Center for Computational Sciences, University of Tsukuba)
17/07/2015, 14:20
We present our updated study on charmonia and bottomonia at finite temperature with quenched ensembles on large and fine isotropic lattices. Simulations have been performed by using the standard plaquette gauge and the $O(a)$-improved Wilson fermion actions in a region of quark mass for charmonia to bottomonia in order to investigate difference of in-medium behavior between them. We show...
Ivan Horvath
(University of Kentucky)
17/07/2015, 14:20
We describe our recent proposal that distinct phases of vector-like gauge
theories with fundamental quarks translate into specific types of
low-energy behavior in Dirac spectral density. The resulting scenario
is built around new evidence substantiating the existence of a phase
characterized by bimodal (anomalous) density, and corresponding
to deconfined dynamics with broken valence...
Prof.
Masanori Okawa
(Hiroshima University)
17/07/2015, 14:20
We propose a new method to calculate meson propagators in the large N limit from twisted space-time reduced model. Preliminary results of meson spectra and decay constants are presented.
Mr
Alexander Nikolaev
(Far Eastern Federal University)
17/07/2015, 14:20
We present the results of lattice simulation of $QC_2D$ with two flavors of staggered fermions and non-zero chemical potential (\mu_q). Dependencies of the Polyakov loop, chiral condensate and baryon number density on \mu_q were studied. We found, that raising of the baryon chemical potential leads to the chiral symmetry restoration. At small \mu_q our results for the baryon density agree with...
Mr
Andrew Lawson
(University of Southampton)
17/07/2015, 14:20
The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavour changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays sensitive to the effects of potential New Physics. To discern such New Physics one must be able to control the errors on the Standard Model prediction of...
63.
Chiral Magnetic Conductivity in an interacting lattice model of a parity-breaking Weyl semimetal
Mr
Matthias Puhr
(Regensburg University)
17/07/2015, 14:40
With the recent experimental realization of Dirac and Weyl semimetals it has become possible to study the Chiral Magnetic Effect (CME) in clean table-top experiments. We present results of a mean-field study of the static Chiral Magnetic Conductivity (sCMC) in a simple lattice model of a parity-breaking Weyl semimetal. Our model is given by the lattice Wilson-Dirac Hamiltonian with on-site...
Terry E. Tomboulis
(UCLA)
17/07/2015, 14:40
We study lattice $SU(N_c)$ gauge theories with massless staggered fermions at finite quark chemical potential $\mu$. At strong coupling such theories have been studied with a variety of techniques such as mean field, monomer-dimer representations and MC simulations. Here we employ a new cluster expansion which has recently been shown to converge for large $\mu$ and small $\beta$. Extension...
Mr
Takahiro Doi
(Kyoto University)
17/07/2015, 14:40
We investigate contribution to the Polyakov loop fluctuations from each Dirac mode. The Polyakov loop fluctuations are sensitive probes for the quark deconfinement even if considering dynamical quarks. We derive analytical relations between the Polyakov loop fluctuations and Dirac modes on the temporally odd-number lattice, where the temporal lattice size is odd, with the normal non-twisted...
Dr
Xu Feng
(Columbia University)
17/07/2015, 14:40
As flavor changing neutral current processes, rare kaon decays K -> pi nu nu-bar are highly suppressed in the standard model and thus provide ideal probes for the observation of new physics effects.
Given the importance of rare kaon decays, the CERN NA62 experiment aims at an observation of O(100) events of K+ -> pi+ nu nu-bar decay and a 10%-precision measurement of the branching ratio in...
Dr
Alessandro Amato
(University of Helsinki)
17/07/2015, 14:40
It is well known that the topology of gauge configurations generated
in a Markov Monte-Carlo chain freezes as the continuum limit
is approached. The corresponding autocorrelation time increases
exponentially with the inverse lattice spacing, affecting the ergodicity
of the simulation. In SU(N) gauge theories for large N this problem sets
in at much coarser lattice spacings than for N=3....
Mr
Atsuro Ikeda
(Osaka Universitiy)
17/07/2015, 14:40
We study the charmonium spectral functions with finite momentum
from lattice Euclidean correlators using the maximum entropy method.
In medium, the spectral function of vector channel with finite momentum
is decomposed into transverse and longitudinal components
because of the lack of Lorentz invariance.
We investigate these spectral functions, their
residues and the dispersion relations...
Prof.
Norman Christ
(Columbia University)
17/07/2015, 15:00
We will discuss the theoretical framework and initial results for the lattice QCD calculation of the long-distance contributions to $\epsilon_K$, the measure of indirect CP violation in $K_L$ decay. A proof-of-principle calculation has been carried out on a $24^3\times 64$ lattice volume with an inverse lattice spacing of 1.73 GeV and pion mass of 329 MeV. A complete calculation will be...
Dr
Pavel Buividovich
(Regensburg University)
17/07/2015, 15:00
I present a general framework for constructing Diagrammatic Monte-Carlo algorithms for large-N quantum field theories, which is based on the stochastic solution of the full untruncated hierarchy of Schwinger-Dyson equations and is an extension of the approach proposed in arXiv:1104.3459, arXiv:1009.4033. The algorithms are capable of constructing both weak- or strong-coupling expansions which...
Dr
Maksim Ulybyshev
(Regensburg University)
17/07/2015, 15:00
Recent experimental results [Nature Physics, 8 (2012) 550 and Nature 505 (2014) 528] indicate that graphene turns into insulator in sufficiently strong magnetic field. However, the exact nature of this state is still elusive and there are large discrepancies between theoretical predictions and experimental results.
To resolve this discrepancies extensive simulations of graphene in external...
Mr
Johannes Weber
(Technical University Munich)
17/07/2015, 15:00
We calculate the correlation function of Polyakov loops and the cyclic Wilson loops in 2+1 flavor QCD at non-zero temperature.
We also study the correlation function of Wilson lines in Coulomb gauge.
In our investigations we use the highly improved staggered quark (HISQ) action and lattices with temporal extent Nt=4,6,8,10 and 12.
At high temperatures we compare our numerical results with...
Prof.
Leonid Glozman
(University of Graz)
17/07/2015, 15:00
A large degeneracy of mesons of given spin has been discovered upon reduction of the quasi-zero modes of the Dirac operator in a dynamical
simulation. One expects a priori, that upon elimination of the quasi-zero modes of the Dirac operator, the chiral symmetry should be restored, since the quark condensate of the vacuum is connected with the density of the quasi-zero modes. However, it has...
143.
Thimble regularization at work besides toy models: from Random Matrix Theory to Gauge Theories.
Mr
Giovanni Eruzzi
(University of Parma and INFN)
17/07/2015, 15:00
Thimble regularization as a solution of the sign problem has been successfully put at work for a few toy models. Given the non trivial nature of the method (also from the algorithmic point of view) it is compelling to provide evidences that it works for realistic models.
A chiral random matrix theory has been studied in detail. The known analytical solution shows that the model is non-trivial...
AMARJIT SONI
(Brookhaven National Lab)
17/07/2015, 15:20
It has been been clear for past many years that in low energy observables new physics can only appear as a perturbation. Therefore precise theoretical predictions and precise experimental measurements have become rather mandatory. Here we draw attention to the significant advances that have been made on the lattice in recent years in K=> pi pi, Delta_M_K, long- distance part of epsilon_K and...
Pedro Bicudo
(IST, Univ. Lisboa)
17/07/2015, 15:20
Covariant $R_\xi$ gauge fixing is notoriously difficult for large lattice volumes, large $\xi$ and small $N_c$. We thoroughly test different convergence techniques, which allows the gauge fixing of lattice configurations with a total volume of (3.25 fm)$^4$, up to $\xi=0.5$. We are able to study the gluon propagator in the infrared region and its dependence on the gauge fixing parameter...
Mr
Denis Boyda
(Far Eastern Federal University)
17/07/2015, 15:20
There was a long time disagreement in literature between theoretical calculations and experimental data about conductor-insulator phase transition in graphene. This contradiction was resolved in the papers [Phys. Rev. Lett. 111, 56801 (2013)] and [Phys. Rev. B 89, 195429 (2014)] where chiral condensate was studied taking into account screening of Coulomb potential by $\sigma$-electrons of...
Mr
Semen Valgushev
(University of Regensburg)
17/07/2015, 15:20
It is known that the 1/N expansion in the Gross-Witten U(N) matrix model is divergent and leading divergence in the weak coupling regime is governed by instanton which is associated with eigenvalue tunneling. However, it was not known what triggers divergences in the strong coupling phase where instantons disappear. To address this problem, we numerically study structure of saddle points in...
Attila Pasztor
(University of Wuppertal)
17/07/2015, 15:20
We study the correlators of Polyakov loops, and the corresponding gauge invariant free energy of a static quark-antiquark pair in 2+1 flavor QCD at finite temperature. Our simulations were carried out on Nt = 6, 8, 10, 12, 16 lattices using a Symanzik improved gauge action and a stout improved staggered action with physical quark masses. The free energies calculated from the Polyakov loop...
Dr
Francesco Di Renzo
(University of Parma and INFN)
17/07/2015, 15:20
A final goal for thimble regularization of lattice field theories is the application to lattice QCD and the study of the phase diagram.
Gauge theories pose a number of conceptual and algorithmic problems, some of which can be addressed even in the framework of toy models. We report on our progresses in this field, starting in particular from first successes in the study of one link models.
Dr
Syo Kamata
(Rikkyo Univ.)
17/07/2015, 15:40
We investigate the (0+1) dimensional Thirring model at finite chemical potential by HMC simulations based on the Lefschetz thimble formulation of path-integration. We adopt the lattice model defined with staggered fermion and a compact link field for the auxiliary vector field. We firstly find the critical points (saddle points) under the assumption that the complexified link field is...
Prof.
Kei-Ichi Kondo
(Chiba University)
17/07/2015, 15:40
In this talk we give an analytical derivation for the existence of the confinement/deconfinement phase transition at finite temperature in Yang-Mills theory. Moreover, we give a numerical estimate on the transition temperature $T_d$ in the form of the ratio to a gauge-invariant gluon mass $M(T)$ measured on the lattice. For this purpose, we use the functional renormalization-group equation...
Dr
Yasufumi Araki
(Institute for Materials Research, Tohoku University)
17/07/2015, 15:40
We study the strong correlation effect from Coulomb interaction in two- and three-dimensional Dirac semimetals. Effective field theory for the interacting Dirac semimetals can be constructed in terms of quantum electrodynamics (QED). We propose a U(1) lattice gauge theory formulation with the internal degrees of freedom, such as spin and orbitals (pseudospin), explicitly. In the strong...
Michael Engelhardt
(NMSU)
17/07/2015, 15:40
An exploration of nucleon TMD observables at a substantially lower
pion mass, 170 MeV, than used in previous lattice TMD calculations
is presented. On a corresponding RBC/UKQCD DWF ensemble, TMDs are
extracted from nucleon matrix elements of a bilocal quark operator
containing a staple-shaped gauge link. Appropriate TMD ratios are
constructed to cancel divergences associated with the...
Prof.
Goro Ishiki
(University of Tsukuba)
17/07/2015, 15:40
Some matrix models have been proposed as a non-perturbaive formulation of string theories. In the matrix model formulation of string theories, configurations of strings or D-branes are described by a set of Hermitian matrices. Here, we propose a new class of observables in matrix models, which are made of the Hermitian matrices and encode geometric information of the strings or D-branes. By...
Marco Cè
(Scuola Normale Superiore, Pisa & INFN, Sezione di Pisa)
17/07/2015, 15:40
We report the results of a study of the distribution of the topological charge of the SU(3) Yang–Mills theory: we estimate the second and fourth cumulant with high precision in order to measure the deviation from the normal distribution. The computation is done on the lattice implementing a naïve discretization of the topological charge evolved with the Yang–Mills gradient flow. A range of...
Mr
Hai-Tao Shu
(Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics,Central China Normal University)
17/07/2015, 16:30
All the information of quantum states are encoded in their spectral functions.
The reconstruction of the spectral function from the corresponding Euclidean correlation function is, however, a typical ill-posed problem as an analytic continuation from imaginary time to real time is required. The commonly used Maximum Entropy Method (MEM) is based on the Bayesian interference and its output...
Dr
Taichi Kawanai
(Forschungszentrum Jülich GmbH)
17/07/2015, 16:30
We report on updates of our $B$-physics program using domain-wall light quarks and nonperturbatively tuned, relativistic $b$-quarks by adding measurements obtained with dynamical and physical light quarks. We present progress towards improved determinations of the $B$-meson decay constant $f_B$, the ratio $f_{B_s}/f_B$, and the $B\to \pi \ell\nu$ semi-leptonic form factor. Our results are...
Prof.
Richard Brower
(Boston University)
17/07/2015, 16:30
Viable non-perturbative methods for quantum field theories on curved
manifold are difficult. By adapting features from both the
traditional finite element methods (FEM) and simplicial Regge
calculus we are developing a Quantum Finite Element Method(QFEM).
To test the QFEM approach, we study the $\lambda \phi^4$ on the
simplicial lattice for the Riemann Sphere. To reach the
...
Prof.
Akira Ohnishi
(Yukawa Institute for Theoretical Physics, Kyoto University)
17/07/2015, 16:30
Understanding the QCD phase diagram from first principles is one of the ultimate goals in nuclear and particle physics. The largest obstacle towards this goal is the sign problem in lattice QCD at finite chemical potential. The statistical weight is reduced by the average phase factor and it becomes difficult to obtain precise results in the phase reweighting method.
If we know the amount...
Prof.
Alexander Molochkov
(School of Biomedicine, Far Eastern Federal University)
17/07/2015, 16:30
The most important probes for the phase states of a four-dimensional gauge field theory are the Wilson and t’Hooft line operators that are defined on one-dimensional curves in the space-time. However, for more detail understanding of four-dimensional gauge field theory dynamics and vacuum topology we need additional probes expressed by operators defined on the subspaces with higher dimensions....
Akihiro Shibata
(Computing Research Center, KEK)
17/07/2015, 16:50
We have pointed out that the SU(3) Yang-Mills theory has a new way of reformulation
using new field variables (minimal option), in addition to the conventional option
adopted by Cho, Faddeev and Niemi (maximal option).
The reformulation enables us to change the original non-Abelian gauge field into
the new field variables such that one of them called the restricted field gives
the...
Mr
Edwin Lizarazo
(University of Southampton)
17/07/2015, 16:50
We show first results for the computation of semi-leptonic form factors
for rare $B$ decays focusing in particular on $B \to K^{(*)} \ell^+ \ell^-$ and $B_s \to \phi \ell^+ \ell^-$. Our setup uses domain-wall light quarks, relativistic $b$ quarks, and the RBC/UKQCD 2+1 flavor gauge field configurations with domain-wall fermions and the Iwasaki gauge action.
Dr
hirokazu Kobayashi
(Intel K. K.)
17/07/2015, 16:50
We implemented lattice QCD on Xeon Phi coprocessor using intrinsics as vectorization method, and OpenMP and MPI as parallelization method. Our implementation uses double precision conjugate gradient (CG) solver which also supports multi-shift CG.
We present our optimization methodology and performance for key steps in CG algorithms.
Dr
George Fleming
(Yale University)
17/07/2015, 16:50
We demonstrate the quantum finite element method (QFEM) by computing known properties of the 2-D Wilson-Fisher fixed point using scalar field theory on 2-sphere.
145.
The density of states approach at finite chemical potential: a numerical study of the Bose gas.
Dr
Roberto Pellegrini
(The University of Edinburgh)
17/07/2015, 16:50
Recently, a novel algorithm for computing the density of states in statistical systems and quantum field theories has been proposed. The same method can be applied to theories at finite density affected by the notorious sign problem, reducing a high-dimensional oscillating integral to a more tractable one-dimensional one. As an example we applied the method to the relativistic Bose gas.
Mr
Florian Meyer
(Bielefeld University, Germany)
17/07/2015, 16:50
We present new results on the reconstruction of mesonic continuum spectral
functions for three temperatures between 1.1Tc and 1.5Tc in quenched QCD. Making use of
non-perturbatively improved clover Wilson valence quarks allows for a clean
extrapolation of measured correlator data to the continuum. We found that the vector
correlation function is almost temperature independent in the...
Dr
Oliver Witzel
(University of Edinburgh)
17/07/2015, 17:10
Using our well established setup of domain-wall light quarks and nonperturbatively tuned, relativistic $b$-quarks we extend our $B$-physics program to the computation of $B$-meson bag parameters and their ratio $\xi$. We present first results based on the RBC/UKQCD 2+1 flavor gauge field configurations with domain-wall fermions and the Iwasaki gauge action at two lattice spacing of 0.086 fm...
Dr
Mario Schroeck
(INFN - Roma Tre)
17/07/2015, 17:10
We present the implementation of twisted mass fermions within the QPhiX code package along with an interface to tmLQCD. We analyze the performance on Intel Xeon Phis and Intel Xeon Haswell CPUs. On the latter we find a speedup of larger than 4x for the mixed precision conjugate gradient inverter.
Ms
Chrisanthi Praki
(Swansea University)
17/07/2015, 17:10
Following a recent study of nucleon parity doubling at finite temperature from the computation of the two-point nucleon correlators, we study the spectral functions of free baryons at finite temperature. A full analytic review of the spectral densities in the continuum is presented along with a comparison with numerical results. Particular attention will be given to lattice artifacts at higher...
Dr
Vitaly Bornyakov
(FEFU, Vladivostok)
17/07/2015, 17:10
We study Landau gauge transverse and longitudinal gluon propagators at non-zero
temperature in close vicinity of the phase transition in SU(2) gluodynamics.
We compute the screening mass and the electric-magnetic asymmetry of the
A**2 condensate. Our goal is to provide results free of finite volume and
Gribov copies systematic effects and with small scaling violations.
Mr
Pascal Toerek
(University of Graz)
17/07/2015, 17:10
In this contribution we apply a variant of the density of states method to the Z3 spin model with a chemical potential. We use a restricted Monte Carlo strategy to compute restricted expectation values and study their dependence on a free parameter \lambda which enters in the Boltzmann weight. When expressed in terms of the density, the expectation values are well known functions of \lambda...
Mr
Andrew Gasbarro
(Yale University)
17/07/2015, 17:10
Recent efforts have been made to study conformal field theories in radial quantization on the lattice. The lattice necessarily breaks spherical symmetry down to icosahedral symmetry, so efforts must be made to restore spherical symmetry — even at the classical level — by clever construction of the action. Linear finite elements have been shown to improve the spectrum of the Laplacian. In...
Dr
Hidekatsu Nemura
(Center for Computational Sciences, University of Tsukuba)
17/07/2015, 17:30
We present our recent effort to develop the CUDA code to measure the Nambu-Bethe-Salpeter (NBS) wave function of various baryon-baryon systems on the lattice, which is a primary quantity to make a first-principle calculation of nuclear force and hyperonic-nuclear forces from lattice QCD. Not only the nucleon-nucleon (NN) but also the hyperon-nucleon (YN) and hyperon-hyperon (YY) interactions...
Francesca Cuteri
(University of Calabria)
17/07/2015, 17:30
An attempt to adapt the study of color flux tubes to the case of finite temperature has been made.
The field is measured through a connected correlator of Wilson loop and plaquette in the spatial sub-lattice. Still the profile of the flux tube resembles the transverse field distribution around an isolated vortex in an ordinary superconductor.
The temperature dependence of all the parameters...
Mr
Mario Giuliani
(University of Graz)
17/07/2015, 17:30
We study an effective theory for Polyakov loops at finite density (SU(3) spin model) using the density of states (DoS) method. We generalize a recently developed variant of DoS, the so-called functional fit approach (FFA) for systems with continuous degrees of freedom (compare also the related talk by P. Törek). We show that the density of states can be computed with sufficiently high accuracy...
Prof.
Sinya Aoki
(Kyoto University)
17/07/2015, 17:30
We propose a method, which encodes the information of a $d$ dimensional quantum field theory into a $d+1$ dimensional gravity in the $1/N$ expansion. We first construct a $d+1$ dimensional field theory from the $d$ dimensional one via the gradient flow equation, whose flow time $t$ represents the energy scale of the system such that $t¥rightarrow 0$ corresponds to the ultra-violet (UV)...
Chris Allton
(Swansea University)
17/07/2015, 17:30
The spectrum of nucleons and their parity partners is studied as a function of temperature across the deconfinement transition. We analyse our results using the correlation functions directly, and the Maximum Entropy Method. Both techniques show that there is degeneracy (i.e. parity restoration) in the parity partners' ground states above T_c. This in accordance with the expectation that...
Dr
Antoine Gérardin
(Laboratoire de Physique Corpusculaire (LPC))
17/07/2015, 17:30
We will present our results for the radial distributions of the axial density in the heavy-light B meson in the static limit of HQET: $\langle B(\vec{p}) | A_{\mu}(\vec{r}) | B^{*(\prime)}(\vec{p}^{\ \prime}, \lambda) \rangle$. Here, $r$ is the distance between the static heavy quark and the insertion of the axial current acting like a probe. Using the Generalized Eigenvalue Problem, we are...
Prof.
Christof Gattringer
(University of Graz)
17/07/2015, 17:50
We show that the massless Schwinger model with staggered fermions can be represented with dual variables which are loops for the fermions and surfaces for the gauge fields. In the dual form the complex action problem of the conventional representation at finite chemical potential or non-vanishing theta-angle is absent, and dual Monte Carlo simulations are possible at arbitrary values of these...
Mr
Jun Doi
(IBM Research - Tokyo)
17/07/2015, 17:50
As supercomputers are shifting from peta-scale to exa-scale, computers with accelerators such as GPUs, MICs and FPGAs have become one of the big trends of supercomputer because of their low energy consumption and high density. Now IBM’s POWER processor has quite new power, Nvidia’s Tesla GPU brings huge computational capability. It is important for us to understand how this new POWER+GPU...
Hidekazu Tsukiji
(YITP, Kyoto univ.)
17/07/2015, 17:50
Understanding the themalization process in a pure quantum system is a challenge in theoretical physics. In this work, we explore possible thermalization mechanism in Yang-Mills(Y-M) theory by using a positive semi-definite quantum distribution function called Husimi function which is given by a coarse graining of Wigner function within the minimal uncertainty. Then entropy is defined in terms...
Prof.
Noboru KAWAMOTO
(Hokkaido University)
17/07/2015, 17:50
Recently we have proposed a lattice SUSY formulation which we may call super doubler approach, where chiral fermion species doublers are identified as super partners of extended supersymmetry. We claim that the super symmetry is exactly kept on the lattice. However the formulation is nonlocal and breaks lattice translational invariance. We argue that these features cause no fundamental...
Prof.
Hideo Suganuma
(Kyoto University)
17/07/2015, 17:50
We study the static three-quark (3Q) potential with high statistics in SU(3) lattice QCD at the quenched level. For all the distances, the 3Q potential is found to be well described by the Y-Ansatz, i.e., one-gluon-exchange Coulomb plus Y-type linear potential.
As a remarkable fact, we find that the quark confinement force in the 3Q system can be perfectly described only with Abelian...
Dr
Alfonso Sastre
(University of Wuppertal)
18/07/2015, 09:00
We present an update of our lattice QCD calculation of the connected contribution to the hadronic vacuum polarization.
We discuss different evaluations procedures (including the moment base approach and Pade fits) and the corresponding systematic errors.
Dr
Alexei Bazavov
(University of California, Riverside/University of Iowa)
18/07/2015, 09:00
We present a gauge-invariant effective action for the Abelian Higgs model in 1+1 dimensions. It is constructed by integrating out the gauge field and then using the hopping parameter expansion. The latter is tested with Monte Carlo simulations for small values of the scalar self-coupling. In the opposite limit, at infinitely large self-coupling, the Higgs mode is frozen and the partition...
Mr
Alessandro Nada
(Università di Torino)
18/07/2015, 09:00
We present a novel lattice calculation of the equation of state of SU(2) Yang-Mills theory in the confining phase.
We show that a gas of massive, non-interacting glueballs describes remarkably well the results, provided that a bosonic closed-string model is used to derive an exponentially growing Hagedorn spectrum for the heavy glueball states with no free parameters.
This effective model...
Mr
Norihiko Kamata
(Tohoku Univ)
18/07/2015, 09:00
Recently, the Yang-Mills gradient flow method has continued to develop remarkably. The most successful application is demonstrated in an accurate determination of a reference scale. However, there is still room for improvement with respect to the lattice gradient flow, where some lattice artifacts are found to be non-negligible. Following a recent paper by Fodor et al. (arXiv:1406.0827), we...
Dr
Guido Cossu
(KEK High Energy Accelerator Research Organization)
18/07/2015, 09:00
We report the results of our finite temperature investigation of the
axial symmetry restoration at finite temperature. We simulated two flavors of domain-wall fermions at several volumes and lattice spacings.
After taking into account the systematic errors from the violation of the Ginsparg-Wilson relation,
our results show that in the chiral limit there is a strong suppression
of the...
Mr
Stefano Piemonte
(WWU Muenster)
18/07/2015, 09:00
Owing to confinement, the fundamental particles of N=1 Supersymmetric Yang-Mills (SYM) theory, gluons and gluinos, appear only in colourless bound states at zero temperature. Compactifying one space-time dimension with periodic boundary conditions for fermions preserves supersymmetry, and confinement is predicted to persist independently of the length of the compactified dimension. This...
Dr
Balint Toth
(University of Wuppertal)
18/07/2015, 09:20
We report on our lattice QCD calculation of the disconnected contribution to various hadron correlation functions. We discuss different evaluation strategies, optimization of algorithmic parameters and we show first results at a coarse lattice spacing.
Mr
Terukazu Ichihara
(Kyoto University)
18/07/2015, 09:20
In the Beam Energy Scan Phase-1 (BES-1), net proton number fluctuations
have been measured in search for the QCD critical point [1].
Finding the critical point is one of the most challenging subjects
also in lattice QCD due to the sign problem. In the strong coupling limit
of QCD, one can investigate the finite density region by employing the
Auxiliary Field Monte-Carlo (AFMC) method [2]...
Mr
Francesco Capponi
(Plymouth University)
18/07/2015, 09:20
We implement two different strategies for the non perturbative determination of the renormalized energy momentum tensor in SU(3) Yang-Mills on the lattice.
Both strategies employ observables built with gauge fields that evolve according to the Yang Mills gradient flow.
In the first case, we use observables computed along the flow in order to define suitable lattice Ward Identities from which...
Dr
Akio Tomiya
(Osaka university)
18/07/2015, 09:20
We study the U(1)A anomaly in two-flavor lattice QCD at finite
temperature using the Ginsparg-Wilson fermions.
The gauge configurations are generated with the Mobius domain-wall
fermion at and above the critical temperature on 32^3x8 and 32^3x12
lattices. We apply the reweighting of the fermion determinant to that of
domain-wall fermion satisfying the GW relation exactly. The results...
Dr
pietro giudice
(muenster university)
18/07/2015, 09:20
The spectrum of N=1 supersymmetric Yang-Mills theory, calculated on the lattice, is presented. The masses have been determined on three different lattice spacings and extrapolated towards vanishing gluino mass. We present the extrapolation to the continuum limit which is consistent with the formation of degenerate supermultiplets.
Dr
Urs Wenger
(Albert Einstein Center for fundamental physics)
18/07/2015, 09:40
The fermion loop formulation naturally separates partition functions into their canonical sectors. Here we discuss various strategies to make use of this for supersymmetric SU(N) Yang-Mills quantum mechanics obtained from dimensional reduction in various dimensions and present numerical results for the separate canonical sectors with fixed fermion numbers. We comment on potential problems due...
Dr
Alejandro Vaquero Avilés-Casco
(INFN Sezione Milano Biccoca)
18/07/2015, 09:40
We compute the disconnected quark loops contributions entering the determination of nucleon observables, by using an N_f = 2 ensemble of twisted mass fermions with a clover term at a pion mass $m_\pi~130$ MeV.
We employ exact deflation and implement all calculations in QUDA, enabling us to achieve large statistics and a good signal.
Roman Höllwieser
(NMSU / VUT)
18/07/2015, 09:40
We apply the relative weights method to extract an effective Polyakov line action, at finite chemical potential, from an underlying SU(3) lattice gauge theory with dynamical fermions. The center-symmetry breaking terms in the effective theory are fit to a form suggested by the hopping-parameter expansion, and the effective action is solved at finite chemical potential by a mean field...
Dr
Yuya Shimizu
(RIKEN Advanced Institute for Computational Science)
18/07/2015, 09:40
We estimate the critical point of the Schwinger model in the theta vaccum by taking the continuum limit of Wilson's lattice formulation. The decorated tensor renormalization group which has been recently proposed by Dittrich et al. is employed for numerical investigation. We compare our numerical results with those of Byrnes et al., which were derived from Kogut-Susskind's lattice formulation...
Prof.
Hiroshi Suzuki
(Kyushu University)
18/07/2015, 10:00
We develop a background field method and associated gauge fixing prescription in gradient flow equations. By using this formulation, we carry out non-diagramatic one-loop computations of the small flow time expansion of gauge invariant composite operators, aiming for the application to the energy-momentum tensor and the flavor-singlet axial-vector current on the lattice.
Mr
Daniel Schmidt
(Theoretisch-Physikalisches Institut, Jena University)
18/07/2015, 10:00
The Thirring model is a four fermion theory with vector interaction. We study it in three dimensions, where it is closely related to QED and other models used to describe properties of graphene. In addition it is a good toy model to study chiral symmetry breaking, since a phase with broken chiral symmetry is present for the model with one fermion flavour. On the other hand, there is no such...
Mr
Philipp Scior
(Technische Universitaet Darmstadt)
18/07/2015, 10:00
We study QCD-like theories at finite density with three-dimensional Polyakov theories for heavy quarks. These effective theories are derived by combined strong coupling and hopping expansion techniques as previously been used for QCD. In particular we investigate the cold and dense regimes of the phase diagrams where one either expects Bose-Einstein condensation of bosonic or a liquid-gas...
Dr
Tim Harris
(Helmholtz Institute Mainz)
18/07/2015, 10:00
We explore the effects of open boundary conditions, as used in the CLS $N_{\mathrm f}=2+1$ ensembles, on nucleon two- and three-point functions, with a view towards studying nucleon form factors on these ensembles. Particular emphasis is put on controlling systematic effects due to the boundaries and excited states, and to the approach to the physical point.
David Schaich
(Syracuse University)
18/07/2015, 10:00
I will present results from numerical studies of maximally supersymmetric Yang--Mills theory, using a new improved lattice action. I will also summarize the improvement procedure, which modifies the moduli equations in order to lift U(1) flat directions without violating the exact supersymmetry preserved at non-zero lattice spacing by the lattice formulation. The resulting improved action...
Dr
Yu Maezawa
(Yukawa Institute for Theoretical Physics, Kyoto University)
18/07/2015, 10:00
By using spatial correlation functions we study thermal modifications of meson states and the restoration of broken symmetries at finite temperature in 2+1 flavor QCD with the Highly Improved Staggered Quarks (HISQ) action.
The spatial correlation functions provide a direct signal for the thermal modification of meson spectral functions and indicate the restoration of chiral and U_A(1)...
Dr
Takuya Kanazawa
(RIKEN iTHES)
18/07/2015, 10:20
The first lattice formulation of Lifshitz-type gauge theories is presented.
While the Lorentz-invariant Yang-Mills theory is not renormalizable in five dimensions, non-Abelian Lifshitz-type gauge theories are renormalizable and asymptotically free. We construct a lattice gauge action and numerically examine the continuum limit and the bulk phase structure.
Mr
Tomomi Sato
(The Graduate University for Advanced Studies)
18/07/2015, 10:20
We study chiral phase transition of two flavor massless QCD in the presence of a finite breaking of U(1) axial symmetry using the corresponding linear sigma model (LSM), in which half of eight scalar fields acquire the mass proportional to the U(1) breaking. Naively, the model is expected to reduce to ordinary O(4) LSM in the infrared limit if the massive degrees of freedom decouple...
Dr
Bjoern Wellegehausen
(Theoretisch-Physikalisches Institut, FSU Jena)
18/07/2015, 10:20
G(2)-QCD is a QCD-like theory that can be simulated with standard Monte-Carlo methods at finite baryon density. It shares many properties with QCD, especially fermionic baryons. In addition also bosonic baryons are present in the theory.
In the talk we review the effect of bosonic and fermionic baryons on the phase diagram at zero temperature and show evidence for a first oder nuclear matter...
Dr
Kengo Kikuchi
(Yukawa Institute for Theoretical Physics, Kyoto University)
18/07/2015, 10:20
We generalize the gradient flow equation for field theories with nonlinearly realized symmetry. We apply the method to two theories, the super Yang-Mills theory in four dimensions and the O(N) nonlinear sigma model in two dimensions. Firstly, applying the formalism to super Yang-Mills theory, we construct the supersymmetric gradient flow equation. Furthermore, choosing an appropriate...
Dr
Arwed Schiller
(Leipzig University)
18/07/2015, 10:20
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use an one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We...
Dr
Georg von Hippel
(University of Mainz)
18/07/2015, 10:40
We extend our study of excited-state effects on nucleon vector form factors to the case of the axial vector and pseudoscalar form factors. Combining information from a variety of different ratios of two- and three-point functions, we are able to extract the form factors $G_A$ and $G_P$ over a range of momentum transfers Q^2; together with the use of different methods to suppress excited-state...
Mr
Masahiro Ishii
(Kyushu University)
18/07/2015, 10:40
We determine temperature (T) dependence of U_A (1) restoration from meson screening masses calculated with 2+1 flavor lattice QCD, using PNJL model with entanglement vertex. The entanglement PNJL (EPNJL) model exhibits the U_A (1) anomaly through the Kobayashi- Maskawa- ’t Hooft (KMT) interaction. T dependence of KMT interaction strength is then determined from the difference between pion and...
Dr
Valentina Forini
(Humboldt University Berlin)
18/07/2015, 10:40
A possible discretization of the Green-Schwarz string in AdS5xS5 background is
discussed and applied to the numerical study of the so-called cusp anomaly f(g).
The latter, a pure function of the coupling g, when studied assuming the integrability of the underlying model, is an example of non-trivial interpolation smoothly connecting weak and strong coupling regimes and testing the AdS/CFT...
Dr
Kazuhiko Kamikado
(Riken)
18/07/2015, 10:40
If the chiral anomaly is effectively restored at finite temperature, the chiral phase transition of 2-flavor QCD with massless quarks is characterised by the symmetry breaking patter U_L(2) x U_R(2) -> U_V(2). Therefore, the order of the phase transition of the U(2) x U(2) scalar model in three dimensions has been extensively studied.
The results of the perturbative renormalization group...
Dr
Christopher Monahan
(University of Utah)
18/07/2015, 10:40
The gradient flow has proved a valuable tool to the lattice community, with a range of applications to a variety of lattice calculations, from scale-setting to renormalisation. In this talk, I will focus on the gradient flow as a tool to suppress power-divergent mixing, a consequence of the hypercubic symmetry of the lattice regulator that is a particular difficulty for calculations of high...
Ms
Susanne Ehret
(University of Edinburgh)
18/07/2015, 10:40
A nonperturbative renormalization prescription for the energy-momentum tensor, based on space-time symmetries along the Wilson flow, has been proposed recently in the context of four-dimensional gauge theories. We extend this construction to the case of a scalar field theory, and investigate its numerical feasibility by studying Ward identities in 3-dimensional phi^4 theory.
In this talk, we...
Prof.
Harvey Meyer
(Johannes Gutenberg-University Mainz)
18/07/2015, 13:00
I will review the status of calculations of thermodynamics quantities, spatial correlation lengths and real-time properties of strongly interacting matter at non-zero temperature. An attempt at a synthesis will be made. Quark number susceptibilities will not be covered here.
Dr
Szabolcs Borsanyi
(University of Wuppertal)
18/07/2015, 13:45
Fluctuations of conserved charges in a grand canonical ensemble can be calculated as derivatives of the free energy with respect to the respective chemical potential. They are directly related to experimentally available observables that describe the hadronization in heavy ion collisions. The same derivatives can be used to extrapolate zero density results to finite chemical potential. We...
Dr
Daisuke Kadoh
(KEK)
18/07/2015, 15:15
Non-perturbative investigations of supersymmetry and superstring theory through lattice simulations are promising research directions. In this talk, I will review the recent progress in lattice supersymmetry, in particular, the numerical verification of the gauge/gravity duality.
Dr
Anna Hasenfratz
(University of Colorado)
18/07/2015, 15:45
The discovery of the Higgs boson in 2012 completed the Standard Model but many puzzles remain. Composite systems where the Higgs boson is a bound state of some new fermion species are viable models to describe beyond-SM phenomenology, but are most likely strongly coupled and require non-perturbative investigations.
In this talk I will review recent lattice calculations that investigate...
