Semi-leptonic and Non-leptonic $B$ meson decays to charmed mesons

We study the semi-leptonic and non-leptonic $B$ weak decays which are governed by the $B\to D^{(\ast )}$ transitions. The branching ratios, CP asymmetries (CPA) and polarization fractions (FA) of non-leptonic decays are investigated in the factorization approximation. The $B\to D^{(\ast )}$ form factors are estimated in the Salpeter method. Our estimation on branching ratios generally agree with the existent experimental data. For CPA and polarizations, comparisons among the FA results, the perturbative QCD predictions and experimental data are made.