Uncertainties in estimating the indirect production of Bc and its excited states via top quark decays at CERN LHC

Main theoretical uncertainties in estimating the indirect production of (bc¯)-quarkonium (Bc− meson and its excited states) via top quark decays, t→(bc¯)+c+W+, are studied within the non-relativistic QCD framework. It is found that the dimensionless reduced decay width for a particular (bc¯)-quarkonium state, Γ¯n=Γn/Γt→W++b, is very sensitive to the c-quark mass, while the uncertainties from the b-quark and t-quark masses are small, where n stands for the eight (bc¯)-quarkonium states up to O(v4): |(bc¯)(S01)1〉, |(bc¯)(S13)1〉, |(bc¯)(P11)1〉, |(bc¯)(PJ3)1〉 (with J=(1,2,3)), |(bc¯)(S01)8g〉 and |(bc¯)(S13)8g〉 respectively. About 108tt¯-pairs shall be produced per year at CERN LHC, if adopting the assumption that all the higher Fock states decay to the ground state with 100% probability, then we shall have (1.038−0.782+1.353)×105Bc− events per year. So the indirect production provides another important way to study the properties of Bc− meson in comparison to that of the direct hadronic production at CERN LHC.