Semileptonic decays $B/B_s\to (D^{(\ast )},D_s^{(\ast )})l{\nu }_l$ in the PQCD approach with the lattice QCD input

Abstract

In this paper, we studied the semileptonic $B/B_s\to (D^{(\ast )},D_s^{(\ast )})l{\nu }_l$ decays in the framework of the standard model (SM) , by employing the perturbative QCD (PQCD) factorization formalism combining with the lattice QCD inputs of the relevant transition form factors. We calculated the branching ratios $\mathcal{B}(B_{(s)}\to D_{(s)}^{(\ast )}l{\nu }_l)$ with $l=(e,\mu .\tau )$ , the ratios of the branching ratios $R(D^{(\ast )})$ and $R(D_s^{(\ast )})$ and other physical observables $P_{\tau }(D_{(s)}^{(\ast )})$, $F_L(D_{(s)}^{\ast })$ and $A_{FB}(\tau )$. The "PQCD+Lattice" predictions for $\mathcal{B}(B\to D^{(\ast )}l{\nu }_l)$ and $R(D^{(\ast )})$ do agree well with those currently available experimental measurements within the errors. For the ratios $R(D_s)$ and $R(D_s^{\ast })$, the "PQCD+Lattice" predictions agree well with other known predictions. For both $P_{\tau }(D^{\ast })$ and $F_L(D^{\ast })$, our theoretical predictions agree well with the measured values within errors. Our theoretical predictions about the considered semileptonic $B/B_s$ decays could be tested in the near future LHCb and the Belle II experiments.

Comments: 25 pages, 3 figures and 6 tables. Figures 2 and 3 are modified, some modifications for text. To be published in Chinese Physics C