@misc{10481/85945,
year = {2023},
month = {9},
url = {https://hdl.handle.net/10481/85945},
abstract = {This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment aτ. The dataset corresponds to an integrated luminosity of 1.44  nb−1 of LHC Pb+Pb collisions at √sNN=5.02  TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of μττ=1.03+0.06−0.05 assuming the standard model value for aτ. To measure aτ, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→μμ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for aτ is −0.057<aτ<0.024.},
organization = {CERN},
organization = {MICINN, Spain},
organization = {COST},
organization = {ERC},
organization = {ERDF},
organization = {Horizon 2020},
organization = {Marie Skłodowska-Curie Actions},
organization = {European Union},
organization = {La Caixa Banking Foundation},
organization = {CERCA Programme Generalitat de Catalunya},
organization = {PROMETEO},
organization = {GenT Programs Generalitat Valenciana, Spain},
organization = {PIC (Spain)},
publisher = {American Physical Society},
title = {Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector},
doi = {10.1103/PhysRevLett.131.151802},
author = {Aad, G. and Aguilar Saavedra, Juan Antonio and Rodríguez Chala, Mikael and Atlas Collaboration},
}