Semileptonic and nonleptonic B decays to three charm quarks: B->J/psi (eta_c) D l nu and J/psi (eta_c) D pi

We evaluate the form factors describing the semileptonic decays $bar{B^0}to J/psi (eta_c) D^+ ell^- bar u_ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $bar{B^0}to J/psi (eta_c) D^+ pi^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $mathcal{BR}(bar{B^0} to J/psi (eta_c) D^+ ell u_ell) simeq 10^{-13}$, $mathcal{BR}(bar{B^0} to J/psi D^+ pi^-) = 3.1 times 10^{-8}$ and $mathcal{BR}(bar{B^0} to eta_c D^+ pi^-) = 3.5 times 10^{-8}$.