We give the first accurate results for B and Bs meson masses from
lattice QCD including the effect of u, d and s sea quarks, and we improve
an earlier value for the Bc meson mass. By using the Highly Improved
Staggered Quark action for u/d, s and c quarks and NRQCD for the b
quarks, we are able to achieve an accuracy in the masses of around 10 MeV. Our
results are: mB = 5.291(18) GeV, mBs = 5.363(11) GeV and mBc =
6.280(10) GeV. Note that all QCD parameters here are tuned from other
calculations, so these are parameter free tests of QCD against experiment. We
also give scalar, Bs0∗, and axial vector, Bs1, meson masses. We find
these to be slightly below threshold for decay to BK and B∗K respectively.Comment: 22 pages, 19 figure