We use lattice QCD to predict the mass of the Bc meson. We use the MILC
Collaboration's ensembles of lattice gauge fields, which have a quark sea with
two flavors much lighter than a third. Our final result is
mBc=6304±12−0+18MeV. The first error bar is a sum in quadrature
of statistical and systematic uncertainties, and the second is an estimate of
heavy-quark discretization effects.Comment: 4 pages, 3 figures; shorten to fit in PRL; published versio