# Joint Annual Meeting of ÖPG and SPS 2021

August 30, 2021 to September 3, 2021
University of Innsbruck
Europe/Zurich timezone

## 【304】On $R_{K}$ and the global significance of new physics in $b \rightarrow s \ell \ell$ decays

Aug 31, 2021, 2:15 PM
15m
Room B

### Room B

Talk Nuclear, Particle- and Astrophysics (FAKT - TASK)

### Speaker

Davide Lancierini (Universitaet Zuerich (CH))

### Description

Ratios of branching fractions such as $R_{K}= \mathcal{B}(B^{+}\rightarrow K^{+}\mu^{+}\mu^{-})/\mathcal{B}(B^{+}\rightarrow K^{+}e^{+}e^{-})$ are clean probes of lepton flavour universality (LFU) violation. LHCb published the most accurate measurement of this observable up to date, yielding a value $3.1\sigma$ away from the Standard Model prediction, providing the first evidence of LFU violation. This is another piece added to the puzzle of flavour anomalies observed in different processes governed by the $b \rightarrow s \ell \ell$ transition. I will give an overview of the measurement of $R_{K}$ and illustrate a method to assess the global significance of the New Physics hypothesis in the $b \rightarrow s \ell \ell$ system taking into account the Look-elsewhere effect.

### Primary authors

Davide Lancierini (Universitaet Zuerich (CH)) Nicola Serra (Universitaet Zuerich (CH)) Patrick Haworth Owen (Universitaet Zuerich (CH))