Tests of lepton universality using $B^0\to K_S^0{\ell }^{+}{\ell }^{-}$ and $B^{+}\to K^{\ast +}{\ell }^{+}{\ell }^{-}$ decays

Abstract

Tests of lepton universality in $B^0\to K_S^0{\ell }^{+}{\ell }^{-}$ and $B^{+}\to K^{\ast +}{\ell }^{+}{\ell }^{-}$ decays where $\ell$ is either an electron or a muon are presented. The differential branching fractions of $B^0\to K_S^0{e}^{+}{e}^{-}$ and $B^{+}\to K^{\ast +}{e}^{+}{e}^{-}$ decays are measured in intervals of the dilepton invariant mass squared. The measurements are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. The results are consistent with the Standard Model and previous tests of lepton universality in related decay modes. The first observation of $B^0\to K_S^0{e}^{+}{e}^{-}$ and $B^{+}\to K^{\ast +}{e}^{+}{e}^{-}$ decays is reported.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-038.html. v2 - Added two more leptoquark references, and fixed formatting bugs in arXiv title and abstract. v3 - Version of paper published in PRL