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

TL;DR

This paper reports measurements of lepton universality in specific B meson decays, finding results consistent with the Standard Model and presenting the first observations of certain decay modes using LHCb data.

Contribution

It provides the first observation of $B^0 o K^0_S e^+ e^-$ and $B^+ o K^{*+} e^+ e^-$ decays and measures their differential branching fractions, testing lepton universality with new experimental data.

Findings

Results are consistent with the Standard Model.

First observation of specific decay modes.

Differential branching fractions measured in dilepton mass intervals.

Abstract

Tests of lepton universality in $B^0\to K^0_S \ell^+ \ell^-$ and $B^+\to K^{*+} \ell^+ \ell^-$ decays where $\ell$ is either an electron or a muon are presented. The differential branching fractions of $B^0\to K^0_S e^+ e^-$ and $B^+\to K^{*+} e^+ e^-$ 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 $B^0 \to K^0_S e^+ e^-$ and $B^+ \to K^{*+} e^+ e^-$ decays is reported.