Quark Masses

I will present a new method to determine quark masses from heavy-light meson masses. The two theoretical foundations of the method are 1) the well-known formula for heavy-light hadron masses in the heavy-quark effective theory, and 2) a new definition of the heavy-quark mass with an elegant treatment of the renormalon problem. Using lattice-QCD data from the Fermilab Lattice and MILC Collaborations, the method yields precision on the charmed and bottom quark masses comparable to the best existing determinations. Using very precise quark-mass ratios, including m_c/m_s from this analysis, we can obtain the most precise determinations of the up-, down-, and strange-quark masses.