Angular observables and branching ratio for $B_s\to \phi {\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ decay

In this paper, an analysis of the $B_s\to \phi {\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ rare decay is presented within the framework of the covariant confined quark model. The $B_s\to \phi$ transition form factors are calculated and then used to compute the branching fractions and angular observables in various $q^2$ bins, including the forward-backward asymmetry $A_{FB}$, the longitudinal polarization $F_L$, and the optimized observables $A_i$ and $S_i$. The results show agreement with the latest experimental data given by LHCb collaboration and compared with available theoretical predictions.