Study of semileptonic ${\bar{B}}^{\ast }\to P\ell {\bar{\nu }}_{\ell }$ decays

Abstract

In anticipation of abundant $B^{\ast }$ data samples at high-luminosity heavy-flavor experiments in the future, the tree-dominated semileptonic ${\bar{B}}_{u,d,s}^{\ast }\to P{\ell }^{-}{\bar{\nu }}_{\ell }$ $(P=D,D_s,\pi ,K)$ decays are studied within the Standard Model. After a detailed calculation of the helicity amplitudes, the theoretical predictions for branching fraction~(decay rate), lepton spin asymmetry, forward-backward asymmetry and ratio $R_D^{\ast (L)}$ are firstly presented. It is found that the CKM-favored ${\bar{B}}^{\ast }\to D{\ell }^{-}{\bar{\nu }}_{\ell }$ decays have relatively large branching fractions of $\mathcal{O}(10^{-9})$$\sim$$\mathcal{O}(10^{-7})$, and are in the scope of running LHC and forthcoming SuperKEKB/Belle-II experiments.

Comments: 18 pages, 2 figures