Prof.
Kieran Holland
(University of the Pacific)
15/07/2015, 18:30
Theoretical Developments
Poster
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
Nonzero Temperature and Density
Poster
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
Algorithms and Machines
Poster
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
Algorithms and Machines
Poster
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
Nonzero Temperature and Density
Poster
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
Applications Beyond QCD
Poster
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
Chiral Symmetry
Poster
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
Weak Decays and Matrix Elements
Poster
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
Standard Model Parameters and Renormalization
Poster
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
Hadron Spectroscopy and Interactions
Poster
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
Nonzero Temperature and Density
Poster
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
Algorithms and Machines
Poster
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
Weak Decays and Matrix Elements
Poster
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
Theoretical Developments
Poster
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
Hadron Spectroscopy and Interactions
Poster
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
Chiral Symmetry
Poster
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
Algorithms and Machines
Poster
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
Hadron Spectroscopy and Interactions
Poster
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
Standard Model Parameters and Renormalization
Poster
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
Physics Beyond the Standard Model
Poster
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
Theoretical Developments
Poster
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
Algorithms and Machines
Poster
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
Standard Model Parameters and Renormalization
Poster
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
Algorithms and Machines
Poster
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
Algorithms and Machines
Poster
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
Algorithms and Machines
Poster
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
Theoretical Developments
Poster
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
Hadron Structure
Poster
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
Physics Beyond the Standard Model
Poster
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
Chiral Symmetry
Poster
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
Applications Beyond QCD
Poster
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
Jun Noaki
(KEK)
15/07/2015, 18:30
Theoretical Developments
Poster
We study the vacuum structure of the SU(3) gauge theory with the flavor number within the conformal region. We perform numerical simulation employing the massless Domain-Wall fermions with the one-step stout smearing.
We investigate a conjecture based on the idea of "the conformal field theories with an IR cutoff", which was recently studied using the Wilson fermions. Dealing with the...
Dr
Hideo Matsufuru
(High Energy Accelerator Research Organization (KEK))
15/07/2015, 18:30
Applications Beyond QCD
Poster
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
Nonzero Temperature and Density
Poster
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
Theoretical Developments
Poster
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
Hadron Spectroscopy and Interactions
Poster
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
Vacuum Structure and Confinement
Poster
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
Physics Beyond the Standard Model
Poster
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
Hadron Spectroscopy and Interactions
Poster
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
Nonzero Temperature and Density
Poster
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
Hadron Spectroscopy and Interactions
Poster
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...
