Article

# Physical results from 2+1 flavor Domain Wall QCD

09/2008;
Source: arXiv

ABSTRACT

We review recent results for the chiral behavior of meson masses and decay constants and the determination of the light quark masses by the RBC and UKQCD collaborations. We find that one-loop SU(2) chiral perturbation theory represents the behavior of our lattice data better than one-loop SU(3) chiral perturbation theory in both the pion and kaon sectors. The simulations have been performed using the Iwasaki gauge action at two different lattice spacings with the physical spatial volume held approximately fixed at (2.7 fm)^3. The Domain Wall fermion formulation was used for the 2+1 dynamical quark flavors: two (mass degenerate) light flavors with masses as light as roughly 1/5 the mass of the physical strange quark mass and one heavier quark flavor at approximately the value of the physical strange quark mass. On the ensembles generated with the coarser lattice spacing, we obtain for the physical average up- and down-quark and strange quark masses m_ud(MSbar,2GeV)=3.72(0.16)_stat(0.33)_ren(0.18)_syst MeV and m_s(MSbar,2GeV)=107.3(4.4)_stat(9.7)_ren(4.9)_syst MeV, respectively, while we find for the pion and kaon decay constants f_pi=124.1(3.6)_stat(6.9)_syst MeV, f_K=149.6(3.6)_stat(6.3)_syst MeV. The analysis for the finer lattice spacing has not been fully completed yet, but we already present some first (preliminary) results. Comment: 7 pages, 3 figures, 1 table, talk presented at the XXVI International Symposium on Lattice Field Theory, 14-19 July 2008, Williamsburg, VA, USA

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• "The calculations were performed on three 32 3 × 64 2+1-flavor domain wall fermion gauge ensembles generated by the RBC and UKQCD collaborations [4] [5] with the input light quark masses set to am l = 0.004, 0.006 and 0.008 and the strange quark mass fixed to am s = 0.03. The corresponding pion masses are roughly 297 MeV, 355 MeV and 403 MeV. "
##### Article: Nucleon electromagnetic form factors with 2+1 flavors of domain wall fermions
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ABSTRACT: We present the recent high-statistics calculations of the nucleon electromagnetic form factors with fully dynamical domain wall fermions on the 32^3x64 lattices generated by the RBC and UKQCD collaborations, with pion masses at roughly 297 MeV, 355 MeV and 403 MeV. We study the phenomenological fits to the momentum transfer dependence of the form factors and investigate chiral extrapolations for the Dirac radius, Pauli radius and the anomalous magnetic moment using two variants of chiral effective field theories, the small scale expansion (SSE) and covariant baryon chiral perturbation theory. Comment: Talk given at the XXVII International Symposium on Lattice Field Theory, Beijing, China, July 26-31, 2009. 8 pages, 9 figures
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##### Article: Aspects of Precision Calculations of Nucleon Generalized Form Factors with Domain Wall Fermions on an Asqtad Sea
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ABSTRACT: In order to advance lattice calculations of moments of unpolarized, helicity, and transversity distributions, electromagnetic form factors, and generalized form factors of the nucleon to a new level of precision, this work investigates several key aspects of precision lattice calculations. We calculate the number of configurations required for constant statistical errors as a function of pion mass, describe the coherent sink method to help achieve these statistics, examine the statistical correlations between separate measurements, study correlations in the behavior of form factors at different momentum transfer, examine volume dependence, and compare mixed action results with those using comparable dynamical domain wall configurations. We also show selected form factor results and comment on the QCD evolution of our calculations of the flavor non-singlet nucleon angular momentum.