Semileptonic decays Bc → (ηc, J/Ψ)lν in the perturbative QCD approach

Abstract

In this paper we study the semileptonic decays of B−c → (ηc, J/Ψ)l−ν̄1. We first evaluate the Bc → (ηc, J/Ψ) transition form factors F0(q2), F+(q2), V(q2) and A0,1,2(q2) by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that: (a) the pQCD predictions for the values of the Bc → ηc and Bc → J/Ψ transition form factors agree well with those obtained by using other methods; (b) the pQCD predictions for the branching ratios of the considered decays are Br(B−c→ηce−ν̄e(μ−ν̄μ)) = (4.41)×10−3, Br(B−c→ηcτ−ν̄τ) = (1.37)×10−3, Br(B−c→J/Ψe−ν̄e(μ−ν̄μ)) = (10.03)×10−3, and Br(B−c→J/Ψτ−ν̄τ) = (2.92)×10−3; and (c) we also define and calculate two ratios of the branching ratios Rηc and RJ/Ψ, which will be tested by LHCb and the forthcoming Super-B experiments.