Covariant light-front approach for B_c decays into charmonium: implications on form factors and branching ratios

Abstract

In this work, we investigate the form factors of B_c decays into J/Psi , psi (2S,3S),eta _c, eta _c(2,S,3,S), chi _{c0}, chi _{c1}, h_c, and X(3872) mesons in the covariant light-front quark model (CLFQM). For the purpose of the branching ratio calculation, the form factors of B_crightarrow D^{(*)}, D^{(*)}_s transitions are also included. In order to obtain the form factors for the physical transition processes, we need to extend these form factors from the space-like region to the time-like region. The q^2 dependence for each transition form factor is also plotted. Then, using the factorization method, we calculate the branching ratios of 80 B_c decay channels with a charmonium involved in each mode. Most of our predictions are comparable to the results given by other approaches. As to the decays with the radially excited-state S-wave charmonia involved, such as psi (2S,3S) and eta _c(2S,3S), two sets of parameters for their light-front wave functions, corresponding to scenario I (SI) and scenario II (SII), are adopted to calculate the branching ratios. By comparing with the future experimental data, one can discriminate which parameters are more favored.