QCD Sum Rules Study of the Semileptonic B_(s)(B^(pm))(B⁰)to D_(s)[1968](D⁰)(D^(pm)) lν Decays

The form factors of the semileptonic $B_{q}\to D_{q}(J^{P}=0^{-})\ell\nu$ with $q=s, u, d$ transitions are calculated in the framework of three point QCD sum rules. Using the $q^2$ dependencies of the relevant form factors, the total decay width and the branching ratio for these decays are also evaluated. A comparison of our results for the form factors of $B\to D\ell\nu$ with the lattice QCD predictions within heavy quark effective theory and zero recoil limit is presented. Our results of the branching ratio are in good agreement with the constituent quark meson model for ($q=s, u, d$) and experiment for ($q= u, d$). The result of branching ratio for $B_{s}\to D_{s}(1968)\ell\nu$ indicates that this transition can also be detected at LHC in the near future.