\({{B}_{s}} \to D_{s}^{{(*)}}\ell {{\nu }_{\ell }}\) and \({{B}_{c}} \to {{M}_{{\bar {c}c}}}{\kern 1pt} l{{\nu }_{\ell }}\) Decays in Covariant Confined Quark Model

In this paper we showed the theoretical predictions within the covariant quark model of branching ratios \({{B}_{s}} \to D_{s}^{{(*)}}\ell {{\nu }_{\ell }}\) and \({{B}_{c}} \to {{M}_{{\bar {c}c}}}{\kern 1pt} l{{\nu }_{\ell }}\) decays. Our results for \({{B}_{s}} \to D_{s}^{{(*)}}\ell {{\nu }_{\ell }}\) are in a good agreement with the data from the latest LHCb experiments as well as lattice quantum chromodynamics simulations. At the same time the theoretical predictions for the ratio \({{\mathcal{R}}_{{J/\psi }}}\) are more than 2σ less than the experimental data. This may indicate on the possibility of New physics effects in this decay.