Exclusive semileptonic and nonleptonic decays of the $B_c$ meson

We study exclusive nonleptonic and semileptonic decays of the $B_c$-meson within a relativistic constituent quark model previously developed by us. For the nonleptonic decays we use the factorizing approximation. We update our model parameters by using new experimental data for the mass and the lifetime of the $B_c$ meson and the leptonic decay constants of the $D$-meson. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the $B_c$ meson and compare our results with the results of other studies. As a guide for further experimental exploration we provide explicit formulas for the full angular decay distributions in the cascade decays $B_c^{-}\to J/\psi (\to l^{+}{l}^{-})+{\rho }^{-}(\to {\pi }^{-}{\pi }^0)$ and $B_c^{-}\to J/\psi (\to l^{+}{l}^{-})+W_{\mathrm{off}\mathrm{\text{−}}\mathrm{shell}}^{-}(\to l^{-}+{\overline{\nu }}_l)$.

Figure 1

Definition of the polar angles $\theta$ and $\theta *$ and the azimuthal angle $\chi$ in the cascade decay $B_c^{-}\to J/\psi (\to l^{+}{l}^{-})+{\rho }^{-}(\to {\pi }^{-}{\pi }^0)$.

Figure 2

Definition of the polar angles $\theta$ and ${\theta }_l$ and the azimuthal angle $\chi$ in the cascade decay $B_c^{-}\to J/\psi (\to l^{+}{l}^{-})+W_{\mathrm{off}\mathrm{\text{−}}\mathrm{shell}}^{-}(\to l^{-}+{\overline{\nu }}_l)$.