Lepton Polarization Asymmetry in $B\to K^{(\ast )}{l}^{+}{l}^{-}$

Abstract

We investigate the longitudinal lepton polarization asymmetry in the exclusive processes $B\to K{l}^{+}{l}^{-}$ and $B\to K^{\ast }{l}^{+}{l}^{-}$. We include both short and long-distance contributions to the asymmetry in our discussions. We find that average values of the polarization asymmetries of the muon and tau for $B\to K^{(\ast )}{\mu }^{+}{\mu }^{-}$ and $B\to K^{(\ast )}{\tau }^{+}{\tau }^{-}$ are $-0.8(-0.7)$ and $-0.2(-0.5)$, respectively.

17 pages (Latex), 4 figures