Search for the charged-lepton-flavor-violating decay $Z\ensuremath{\rightarrow}e\ensuremath{\mu}$ in $pp$ collisions at $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$ with the ATLAS detector

Open Access

Search for the charged-lepton-flavor-violating decay $Z \to e μ$ in $p p$ collisions at $\sqrt{s} = 13 TeV$ with the ATLAS detector

G. Aad et al. (ATLAS Collaboration)

Phys. Rev. D 108, 032015 – Published 25 August 2023

Abstract

A search for the charged-lepton-flavor-violating process $Z \to e μ$ is presented, using $139 {fb}^{- 1}$ of $\sqrt{s} = 13 TeV$ $p p$ collision data collected by the ATLAS experiment at the LHC. An excess in the $e μ$ invariant mass spectrum near the $Z$ boson mass would be a striking signature of new physics. No excess is observed, and an upper limit $B (Z \to e μ) < 2.62 \times 10^{- 7}$ is placed on the branching fraction at 95% confidence level, which is the most stringent limit to date.

Received 25 April 2022
Accepted 7 July 2022

DOI:https://doi.org/10.1103/PhysRevD.108.032015

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.