Precise Charm to Strange Mass Ratio and Light Quark Masses from Full Lattice QCD

By using a single formalism to handle charm, strange, and light valence quarks in full lattice QCD for the first time, we are able to determine ratios of quark masses to 1%. For mc/mₛ we obtain 11.85(16), an order of magnitude more precise than the current PDG average. Combined with 1% determinations of the charm quark mass now possible this gives m̄ₛ(2 GeV)=92.4(1.5) MeV. The MILC result for mₛ/mₗ=27.2(3) yields m̄ₗ(2 GeV)=3.40(7) MeV for the average of u and d quark masses.