CERN Accelerating science

ATLAS Note
Report number	ATLAS-CONF-2023-001
Title	Search for charged-lepton-flavour violating $\mu\tau qt$ interactions in top-quark production and decay with the ATLAS detector at the LHC
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Publication	2023
Imprint	05 Jan 2023
Number of pages	27
Note	All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2023-001
In:	Miami 2022, Miami, Us, Us, 14 - 20 Dec 2022
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	charged lepton flavour violation ; charged ; lepton ; flavour ; violation ; muon ; tau ; muon-tau ; top ; top quark ; top-quark ; rare ; decay ; effective field theory ; EFT ; wilson coefficient ; dim6top ; TOP ; EXOTICS
Abstract	A search for charged-lepton-flavour violating $\mu\tau qt$ interaction is presented, considering both in top-quark production and decay. The data analysed corresponds to $139 \textrm{fb}^{-1}$ of proton--proton collisions at a centre-of-mass energy of $\sqrt{s}= 13$ TeV recorded by the ATLAS detector at the Large Hadronic Collider. The analysis targets events containing two muons, a hadronically decaying tau lepton and at least one jet, with exactly one $b$-tagged jet, produced by a $\mu\tau qt$ interaction in top-quark production or decay. No excess above the Standard Model background is observed and limits are set on the charged-lepton-flavour violation branching ratio of $\text{BR}(t \to \mu\tau q) < 11 \times 10^{-7}$. Wilson coefficient limits, dependent on the flavour of the associated light quark and the Lorentz structure of the coupling, are set ranging from $c_{\ell equ}^{3(2313)} / \Lambda^{2} < 0.11 \textrm{TeV}^{-2}$ for $\mu\tau ut$ to $c_{\ell equ}^{1(2323)} / \Lambda^{2} < 1.9 \textrm{TeV}^{-2}$ for $\mu\tau ct$.
Related document	superseded by: CERN-EP-2024-061

Corresponding record in: Inspire