A precise determination of the Bc mass from dynamical lattice QCD
  We perform a precise calculation of the mass of the B_c meson using unquenched configurations from the MILC collaboration including 2+1 flavours of improved staggered quarks. Lattice NRQCD and the Fermilab formalism are used to describe the b and c quarks respectively. We find the mass of the B_c meson to be 6.304(16) GeV 
I. F. Allison, C.T.H Davies, A.Gray, A.S. Kronfeld, P.B. Mackenzie,   J.N. Simone