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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...
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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 โconnected...
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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.
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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.
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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...
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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 Padรฉ 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...
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Dr
Jeremy Green
(Institut fรผr Kernphysik, Johannes Gutenberg-Universitรคt 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...
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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...
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Hanno Horch
(Uni Mainz)
14/07/2015, 17:10
We present an update of the analysis of the leading order hadronic contribution to the muon g-2 using a high statistics evaluation of the vacuum polarization function (VPF) with O(a)-improved $N_f=2$ Wilson fermions. Partially twisted boundary conditions are used to increase the number of available $Q^2$ points. We employ an extended frequentist's method to study the systematic errors arising...
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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...
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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.
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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...
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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.
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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...
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Mr
Rudolf Roedl
(Universitรคt 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...
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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...
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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, ยฅbeta$ = 2.13 and 2.25. We have estimated the value of the hyperon...
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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...
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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...
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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...
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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.
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Dr
Ross Young
(University of Adelaide)
16/07/2015, 08:30
By considering an appropriate modification of the action, the FeynmanโHellman (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...
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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...
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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...
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Dr
Christian Torrero
(on behalf of the Budapest-Marseille-Wuppertal Collaboration (Centre de Physique Thรฉorique and CNRS, Aix-Marseille Universitรฉ, 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.
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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.
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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...
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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...
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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...
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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...
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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.
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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.
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Dr
Alejandro Vaquero Avilรฉs-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.
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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.
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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...
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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...
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