Chiral Limit and Light Quark Masses in 2+1 Flavor Domain Wall QCD

Abstract

We present results for meson masses and decay constants measured on 24^3x64 lattices using the domain wall fermion formulation with an extension of the fifth dimension of L_s=16 for N_f=2+1 dynamical quark flavors. The lightest dynamical meson mass in our set-up is around 331 MeV, while partially quenched mesons reach masses as low as 250 MeV. The applicability of SU(3)xSU(3) and SU(2)xSU(2) (partially quenched) chiral perturbation theory will be compared and we quote values for the low-energy constants from both approaches. We will extract the average light quark and strange quark masses and use a non-perturbative renormalization technique (RI/MOM) to quote their physical values. The pion and kaon decay constants are determined at those values from our chiral fits and their ratio is used to obtain the CKM-matrix element |V_us|. The results presented here include statistical errors only.