New tests of lepton universality using rare B decays with $K_{S}^{0}$ mesons in the final state at LHCb

by Harry Victor Cliff (University of Cambridge (GB))

Tuesday 19 Oct 2021, 11:00 → 12:00 Europe/Zurich

500/1-001 - Main Auditorium (CERN)

In recent years several intriguing anomalies have been reported in the rare decays of B mesons. Most prominently, in March 2021 a measurement by LHCb of the ratio known as $R_K$ showed 3.1 standard deviation significance for the violation of lepton universality in $B^{+} \rightarrow K^{+} \ell^{+} \ell^{-}$ decays, where $\ell$ is either a muon or an electron. Previous measurements of the ratio $R_{K*}$ using $B^{0}\rightarrow K^{*0} \ell^{+} \ell^{-}$ also hinted at the violation of lepton universality, albeit at a lower statistical significance.

In this seminar we present the first tests at LHCb of lepton universality using these decays’ isospin partners - $B^{0} \rightarrow K^{0}_{S} \ell^{+} \ell^{-}$ and $B^{+} \rightarrow K^{*+} \ell^{+} \ell^{-}$ .

These tests have lower statistical sensitivity than $R_K$ and $R_{K*}$ due to the presence of a $K^0_{\text{S}}$ in the final state. The measurements are performed with data recorded by the LHCb experiment in 2011-2012 and 2016-2018, corresponding to an integrated luminosity of 9 $\text{fb}^{-1}$.

 

The seminar will take place in "hybrid format" with the speaker present in-person in the Auditorium. Note that the occupancy is currently limited to 70 people due to hygiene rules.  If you want to attend in person you must register.

CERN_LHC_Seminar_RKS_RKstplus_19-10-21.pdf

Recording