$B_s\to \varphi l^{+}{l}^{-}$ decays in the topcolor-assisted technicolor model

Abstract

Using the updated form factors within the light-cone QCD sum rule approach, we calculate the new physics contributions to rare semileptonic ${\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-},\varphi {\tau }^{+}{\tau }^{-}$ decays from the new particles appearing in the topcolor-assisted technicolor (TC2) model. In our evaluations, we find that: (i) the branching ratio, normalized forward-backward asymmetry and lepton polarization show highly sensitivity to charged top-pions contributions and little sensitivity to $Z^{\prime }$ contributions. The TC2 enhancements to the branching ratios of these decays can reach a factor of $2\sim 4$; (ii) the NP enhancement to the forward-backward asymmetry of the decay $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ is in the range -9% to 22%, but -10% to 0% for decay $B_s\to \varphi {\tau }^{+}{\tau }^{-}$ compared to the SM predictions; (iii) the TC2 model provide an enhancement of more than 30% to the longitudinal polarization asymmetry $P_L$ for decay $B_s\to \varphi {\mu }^{+}{\mu }^{-}$, but a decrease of about 20% to the transverse polarization asymmetry $P_T$ for the decay $B_s\to \varphi {\tau }^{+}{\tau }^{-}$.

Comments: 19 pages, 6 figures, figures changed, two references added