Search for the lepton-flavour violating decays $B^0 \to K^{*0} \tau^\pm \mu^\mp$

TL;DR

This paper reports the first search for lepton-flavour violating decays of B0 mesons into K*0, tau, and muons, using LHCb data, setting upper limits on their branching fractions due to no observed signal.

Contribution

It provides the first experimental search for specific lepton-flavour violating B0 decays and establishes upper limits on their branching fractions.

Findings

No significant signal observed.

Upper limits set on branching fractions at 90% and 95% confidence levels.

Results constrain new physics models predicting such decays.

Abstract

A first search for the lepton-flavour violating decays $B^0 \to K^{*0} \tau^\pm \mu^\mp$ is presented. The analysis is performed using a sample of proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$. No significant signal is observed, and upper limits on the branching fractions are determined to be ${\cal{B}}(B^0 \to K^{*0} \tau^+ \mu^-)< 1.0$ $(1.2)\times 10^{-5} $ and ${\cal{B}}(B^0 \to K^{*0} \tau^- \mu^+)< 8.2$ $(9.8) \times 10^{-6}$ at the 90% (95%) confidence level.