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

The total decay rate of the (ground state) Bc meson within the framework of the relativistic constituent quark model formulated on the light-front (LF) is investigated. The exclusive semileptonic (SL) and nonleptonic (NL) beauty and charm decays of the Bc meson are described through vector and axial hadronic form factors, which are calculated in terms of a constituent quark model LF wave functions. The latter are derived via the Hamiltonian light-front formalism using as input the update version of the ISGW model. The inclusive SL and NL partial rates are calculated within a convolution approach inspired by the partonic model and involving the same Bc wave function which is used for evaluation of the exclusive modes. The framework incorporates systematically 84 exclusive and 44 inclusive partial rates corresponding to the underlying b-bar → c-bar and c-bar → s quark decays. Based on our approach Γb-bar(Bc) = 0.52± 0.02 ps-1, Γc(Bc) = 0.98 ± 0.07 ps-1 are found, where the theoretical uncertainty is dominated by the uncertainty in the choice of the threshold values at which the hadron continuum stars. For the Bc lifetime we obtained τBc = 0.63 ± 0.03 ps