Probe a family non-universal Z' boson effects in B(s)-> phi mu(+) mu(-)decay

Abstract

Motivated by the recent measurement on $\mathcal{B}({\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-})$ by CDF collaboration, we study the effects of a family non-universal $Z^{\prime }$ boson on rare semileptonic ${\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-}$ decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and normalized forward-backward asymmetry on $Z^{\prime }$ couplings and show that these observables are highly sensitive to new $Z^{\prime }$ contributions. Three limiting scenarios are presented in the detailed analyses. Numerically, within the allowed ranges of $Z^{\prime }$ couplings under the constraints from ${\bar{B}}_s-B_s$ mixing, $B\to \pi K$, ${\bar{B}}_d\to (X_s,K,K^{\ast }){\mu }^{+}{\mu }^{-}$ decays and so on, $\mathcal{B}({\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-})$ and $A_{FB}^{(L)}({\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-})$ could be enhanced by about 96% and $17$ respectively at most by $Z^{\prime }$ contributions. However, $\mathcal{B}({\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-})$ is hardly to be reduced. Furthermore, the zero crossing in $A_{FB}({\bar{B}}_s\to \varphi {\mu }^{+}{\mu }^{-})$ spectrum at low dimuon mass always exists.

Comments: 16 pages, 3 figures, 4 table; accepted by Nucl. Phys. B