Light Quark Masses and the CP violation parameter $\epsilon'/\epsilon$

摘要

We present estimates of light quarks masses using lattice data. Our mainresults are based on a global analysis of all the published data for Wilson andStaggered fermions, both in the quenched approximation and with $n_f=2$dynamical flavors. The Wilson and Staggered results agree after extrapolationto the continuum limit for both the $n_f=0,2$ theories. Our best estimates, inthe MSbar scheme at scale $2 GeV$, are $mbar=3.2(4) MeV$ and $m_s = 90(20) MeV$in the quenched approximation, and $mbar ~ 2.7 MeV$ and $m_s ~ 70 MeV$ for the$n_f=2$ theory. These estimates are significantly smaller than phenomenologicalestimates based on sum rules, but maintain the ratios predicted by chiralperturbation theory. Along with the new estimates of 4-fermion operators, lowerquark masses have a significant impact on the extraction of$\epsilon'/\epsilon$ from the Standard Model.