Semileptonic and nonleptonic decays of B_c mesons to orbitally excited heavy mesons in the relativistic quark model

The form factors of weak decays of the B_c meson to orbitally excited charmonium, D, B_s and B mesons are calculated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. Relativistic effects are systematically taken into account. The form factor dependence on the momentum transfer is reliably determined in the whole kinematical range. The form factors are expressed trough the overlap integrals of the meson wave functions which are known from the previous mass spectra calculations within the same model. On this basis semileptonic and nonleptonic B_c decay rates to orbitally excited heavy mesons are calculated. Predictions for the B_c decays to the orbitally and radially excited 2P and 3S charmonium states are given which could be used for clarifying the nature of the recently observed charmonium-like states above the open charm production threshold.