Abstract
This Letter reports the observation of -lepton-pair production in ultraperipheral lead-lead collisions and constraints on the -lepton anomalous magnetic moment . The dataset corresponds to an integrated luminosity of of LHC collisions at recorded by the ATLAS experiment in 2018. Selected events contain one muon from a -lepton decay, an electron or charged-particle track(s) from the other -lepton decay, little additional central-detector activity, and no forward neutrons. The process is observed in collisions with a significance exceeding 5 standard deviations and a signal strength of assuming the standard model value for . To measure , a template fit to the muon transverse-momentum distribution from -lepton candidates is performed, using a dimuon () control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for is .
- Received 3 May 2022
- Accepted 7 July 2022
DOI:https://doi.org/10.1103/PhysRevLett.131.151802
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.
© 2023 CERN, for the ATLAS Collaboration