The Light Quark Masses from Lattice Gauge Theory

We study the masses of the light quarks with lattice QCD. Most of the dependence on the lattice spacing a , observed previously with Wilson fermions, is removed by an O(a) corrected action. In the quenched approximation, we obtain a strange quark {ovr MS} mass {ovr m}{sub s}(2 GeV)=95(16) MeV, and an average of the up and down quark masses {ovr m}{sub l}(2 GeV)=3.6(6) MeV. Correcting for quenching, the masses likely are 20{percent} to 40{percent} smaller: 54{lt}{ovr m}{sub s}(2 GeV){lt}92 MeV and 2.1{lt}{ovr m}{sub l}(2 GeV){lt}3.5 MeV. We argue that most lattice determinations are consistent with these low values, which are outside the range conventionally given. {copyright} {ital 1997} {ital The American Physical Society}