Search for displaced leptons in $\sqrt{s} = 13$ TeV $pp$ collisions with the ATLAS detector

TL;DR

This paper reports a search for long-lived charged leptons with large impact parameters in proton-proton collisions at 13 TeV, setting new limits on supersymmetric slepton masses and exploring a previously untested signature.

Contribution

It introduces a novel search for displaced leptons with large impact parameters, significantly improving sensitivity to long-lived supersymmetric particles.

Findings

No excess over background observed.

Excluded selectron, smuon, and stau masses up to 720, 680, and 340 GeV respectively.

Provides the most stringent limits to date on these particles.

Abstract

A search for charged leptons with large impact parameters using 139 fb$^{-1}$ of $\sqrt{s} = 13$ TeV $pp$ collision data from the ATLAS detector at the LHC is presented, addressing a long-standing gap in coverage of possible new physics signatures. Results are consistent with the background prediction. This search provides unique sensitivity to long-lived scalar supersymmetric lepton-partners (sleptons). For lifetimes of 0.1 ns, selectron, smuon and stau masses up to 720 GeV, 680 GeV, and 340 GeV are respectively excluded at 95% confidence level, drastically improving on the previous best limits from LEP.