Exclusive and inclusive decays of the Bc meson in the light-front ISGW model

We investigate the total decay width of the (ground-state) Bc meson within the relativistic constituent quark model formulated on the light front (LF). The exclusive semileptonic (SL) and nonleptonic (NL) beauty and charm decays of the Bc meson are described with the aid of the vector and axial hadronic form factors, which are calculated in terms of the overlap of the constituent-quark-model LF wave functions. The latter are derived via the Hamiltonian LF formalism by using the updated version of the ISGW model as an input. The inclusive SL and NL partial rates are calculated within a convolution approach that is inspired by the partonic model and which involves the same Bc wave function as that which is used to evaluate exclusive modes. We predict the partial rates for 84 exclusive and 44 inclusive partial rates corresponding to the underlying b-bar→c-bar and c→s quark decays. On the basis of our approach, we obtain Γb-bar(Bc)=0.52±0.02 ps-1 and Γc(Bc)=0.98±0.07 ps-1, where the theoretical uncertainties are dominated by the uncertainty in the choice of the threshold of the hadron continuum. For the Bc lifetime, we arrive at τBc=0.63±0.02 ps, in good agreement with the prediction obtained by using a nonrelativistic operator-product expansion. We also predict decay rates for many specific weak transitions of Bc. In particular, we obtain 1.7%, 0.1%, and 13.2% for the Bc+→J/ψμ+νμ, Bc+→J/ψπ+, and Bc+→J/ψ+X branching fractions, respectively