Physical results from 2+1 flavor Domain Wall QCD

TL;DR

This paper presents lattice QCD results for meson properties and quark masses using 2+1 flavor Domain Wall fermions, showing SU(2) chiral perturbation theory fits data better than SU(3).

Contribution

It provides new lattice QCD calculations of light quark masses and decay constants with two lattice spacings, highlighting the effectiveness of SU(2) chiral perturbation theory.

Findings

Quark masses: m_ud ≈ 3.72 MeV, m_s ≈ 107.3 MeV

Decay constants: f_pi ≈ 124 MeV, f_K ≈ 150 MeV

SU(2) chiral perturbation theory fits data better than SU(3)

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.