1301.0197 (Wen-Fei Wang et al.)

Semileptonic decays $B/B_s \to (η,\etar,
G)(l^+l^-,l\barν,ν\barν)$ in the perturbative QCD approach beyond
the leading order    [PDF]

Wen-Fei Wang, Ying-Ying Fan, Min Liu, Zhen-Jun Xiao

In this paper we make a systematic study for the semileptonic decays $B/B_s \to (\eta,\etar, G)(l^+l^-,l\bar{\nu},\nu\bar{\nu})$ by employing the perturbative QCD (pQCD) factorization approach. we firstly calculate the form factors $F_{0,+,T}^{B \to \eta_q}(q^2)$ and $F_{0,+,T}^{B_s \to \eta_s}(q^2)$ in the pQCD approach with the inclusion of the next-to-leading-order (NLO) contributions, evaluate the form factors $F_{0,+,T}^{B_{(s)} \to \eta_g}(q^2)$ in the pQCD approach at leading order, and then calculate the branching ratios of the considered decays in the ordinary $\eta$-$\etar$ mixing scheme and the $\eta$-$\etar$-$G$ mixing scheme respectively. From the numerical results and the phenomenological analysis, we found that (a) the NLO contribution to the form factors $F_{0,+,T}^{B_ \to \eta_q}(0)$ and $F_{0,+,T}^{B_s \to \eta_s}(0)$ can provide $\sim 12%$ enhancement to the leading order ones; (b) the NLO pQCD predictions for $Br(B^-\to\etap l^-\bar{\nu}_l)$ with $l=(e,\mu)$ agree well with the data; (c) the pQCD predictions for the branching ratios of other considered decay modes are in a wide range of $10^{-5}$ to $10^{-11}$, and generally have a moderate dependence on the mixing scheme; and (d) in the $\eta$-$\etar$-$G$ mixing scheme, the pQCD predictions for $Br(B^-\to G l^- \bar\nu_l)$ with $l=(e,\mu,\tau)$ are at the level of $10^{-5}$. Our predictions will be tested by LHCb and the forthcoming Super-B experiments.

View original: http://arxiv.org/abs/1301.0197