First determination of the strange and light quark masses from full lattice QCD

We compute the strange quark mass ms and the average of the u and d quark masses mˆ using full lattice QCD with three dynamical quarks combined with the experimental values for the rr and K masses. The simulations have degenerate u and d quarks with masses mu=md=mˆ αs low as ms/8, and two different values of the lattice spacing. The bare lattice quark masses obtained are converted to the MS scheme using perturbation theory at O(αS). Our results are ms MS(2 GeV)576(0)(3)(7)(0) MeV, mˆ MS(2 GeV) 52.8(0)(1)(3)(0) MeV, and ms /mˆ =27.4(1)(4)(0)(1), where the errors are from statistics, simulation, perturbation theory, and electromagnetic effects, respectively.