Measurements of $R(K)$ and $R(K^*)$ with the full LHCb Run 1 and 2 data

About

In this seminar we present the first simultaneous test of muon-electron universality in $B^+ \to K^+ \ell^+\ell^-$ and $B^0 \to K^{*0} \ell^+ \ell^-$ decays, known as $R(K)$ and $R(K^*)$, in two regions of di-lepton invariant mass squared. The analysis operates at a higher signal purity compared with previous analyses and implements a data-driven treatment of residual hadronic backgrounds. The analysis uses the full LHCb Run 1 and 2 data recorded in 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. This analysis is the most sensitive lepton universality test in rare b-decays and the results obtained supersede the previous LHCb measurements of $R(K)$ and $R(K^{*0})$. .

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