Lepton-Flavor-Dependent Angular Analysis of $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$

Abstract

We present a measurement of angular observables and a test of lepton flavor universality in the $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$ decay, where $\ell$ is either $e$ or $\hat{I}¼$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711{\mathrm{fb}}^{-1}$ containing $772\times 10^6$ $B\bar{B}$ pairs, collected at the $\hat{I}\yen (4S)$ resonance with the Belle detector at the asymmetric-energy $e^{+}{e}^{-}$ collider KEKB. The result is consistent with Standard Model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of $2.6\ddot{I}ƒ$.

Submitted to PRL