Effects of neutral $Z^{\prime}$ boson in $B_{s} \to \phi \ell^{+}   \ell^{-}$ decay with polarized $\phi$ and the unpolarized and polarized $CP$   violation asymmetry
  The effects of new neutral $Z^\prime$ boson in $B_{s}\to\phi\ell^{+}\ell^{-}$, when $\phi$ is longitudinal or transverse polarized, are studied. In addition, the implications of $Z^{\prime}$ boson on the unpolarized and polarized $CP$ violation asymmetries, with reference to lepton, are also presented. It is observed that the branching ratio with polarized $\phi$ are quite sensitive to the $Z^{\prime}$ contributions which are coming through the modification of Wilson coefficients $C^{eff}_{9}$ and $C_{10}$. Moreover, the off-diagonal elements of the chiral $Z^{\prime}$ couplings contain new weak phase $\phi_{sb}$ that provide a new source of $CP$ violation. Keeping in view that in the FCNC transitions the $CP$ violation asymmetries are highly suppressed in the SM, we have studied the unpolarized and polarized $CP$ violation asymmetries in $B_{s}\to\phi\ell^{+}\ell^{-}$ decays. Our results indicate that these $CP$ violation asymmetries are remarkably significant and can attribute the any new physics coming through the $Z^{\prime}$ boson. It is hoped that the accurate measurements of these asymmetries will not only help us to establish NP but will also give a chance to determine the precise values of the coupling parameters of the $Z^{\prime}$ boson. 
Ishtiaq Ahmed, M. Jamil Aslam and M. Ali Paracha
hep-ph