Precise heavy-light meson masses and hyperfine splittings from lattice   QCD including charm quarks in the sea
  We present improved results for the B and D meson spectrum from lattice QCD including the effect of u/d,s and c quarks in the sea. For the B mesons the Highly Improved Staggered Quark action is used for the sea and light valence quarks and NonRelativistic QCD for the b quark including O(\alpha_s) radiative corrections to many of the Wilson coefficients for the first time. The D mesons use the Highly Improved Staggered Quark action for both valence quarks on the same sea. We find M_{B_s}-M_B=84(2) MeV, M_{B_s}=5.366(8) GeV, M_{B_c}=6.278(9) GeV, M_{D_s}=1.9697(33) GeV, and M_{D_s}-M_{D}=101(3) MeV. Our results for the B meson hyperfine splittings are M_{B^*}-M_{B}=50(3) MeV, M_{B_s^*}-M_{B_s}=52(3) MeV, in good agreement with existing experimental results. This demonstrates that our perturbative improvement of the NRQCD chromo-magnetic coupling works for both heavyonium and heavy-light mesons. We predict M_{B_c^*}-M_{B_c}=54(3) MeV. We also present first results for the radially excited B_c states as well as the orbitally excited scalar B_c0^* and axial vector B_c1 mesons. 
R.J. Dowdall, C.T.H. Davies, T.C. Hammant, R.R. Horgan
hep-lat