Recent lattice results on the light quark masses

Abstract

I discuss old and new determinations of the light quark masses using lattice QCD. Most lattice results using various approximations can be fit together in a simple picture which is consistent with lower values than conventionally supposed: in the quenched approximation for the strange quark mass in the MS scheme, m s (2 GeV) = 95(16) MeV , and for the average of the u and d quark masses, m l (2 GeV) = 3.6(6) MeV . An estimate of the effects of light quark loops yields answers lower still: m s (2 GeV) in the range 54–92 MeV, and m l (2 GeV) in the range 2.1–3.5 MeV.