$B_c\to B_{sJ}$ form factors and $B_c$ decays into $B_{sJ}$ in covariant light-front approach

Abstract

We suggest to study the $B_s$ and its excitations $B_{sJ}$ in the $B_c$ decays. We calculate the $B_c\to B_{sJ}$ and $B_c\to B_J$ form factors within the covariant light-front quark model, where the $B_{sJ}$ and $B_J$ denote an s-wave or p-wave $\bar{b}s$ and $\bar{b}d$ meson, respectively. The form factors at $q^2=0$ are directly computed while their $q^2$-distributions are obtained by the extrapolation. The derived form factors are then used to study semileptonic $B_c\to (B_{sJ},B_J)\bar{\ell }\nu$ decays, and nonleptonic $B_c\to B_{sJ}\pi$. Branching fractions and polarizations are predicted in the standard model. We find that the branching fractions are sizable and might be accessible at the LHC experiment and future high-energy $e^{+}{e}^{-}$ colliders with a high luminosity at the $Z$-pole. The future experimental measurements are helpful to study the nonperturbative QCD dynamics in the presence of a heavy spectator and also of great value for the spectroscopy study.

Comments: 16 pages, 2 figures