Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
In the covariant light-front quark model, we calculate the form factors of B-c(-) -> J/psi and B-c(-) -> X(3872). Since the factorization of the exclusive processes B-c(-) -> J/psi pi b(-) (K-) and B-c(-) -> X(3872)pi(-) (K-) can be proved in the soft-collinear effective theory, we can easily get the branching ratios for these decays from the form factors. Taking the uncertainties into account, our results for the branching ratio of B-c(-) -> J/psi pi(-)(K-) are consistent with previous studies. By identifying X(3872) as a 1(++) charmonium state, we obtain BR(B-c(-) -> X(3872)pi(-)) = (1.7(-0.6-0.2-0.4)(+0.7+0.1+0.4)) x 10(-4) and BR(B-c(-) -> X(3872)K-) = ((+0.5+0.1+0.3)(1.3-0.5-0.2-0.3)) x 10(-5). Assuming X(3872) to be a 1(--) state, the branching ratios will be one order of magnitude larger than those of the 1++ state. These results can easily be used to test the charmonium description for this mysterious meson X(3872) at the LHCb experiment.