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 a_{τ}. The dataset corresponds to an integrated luminosity of 1.44  nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=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 μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, 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 a_{τ} is -0.057<0.024.

Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector / Betti, Alessandra; DE SALVO, Alessandro; Di Domenico, Antonio.; Dionisi, Carlo.; Bini, Cesare; Luci, Claudio; Morodei, Federico; Lacava, Francesco; SAFAI TEHRANI, Francesco; Artoni, Giacomo; Santi, Lorenzo; Padovano, Giovanni; Martinelli, Luca; Maiani, Luciano; Bauce, Matteo; Gauzzi, Paolo; Gentile, Simonetta; Giagu, Stefano; Ippolito, Valerio. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 131:15(2023), p. 151802. [10.1103/PhysRevLett.131.151802]

Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector

Betti Alessandra;De Salvo Alessandro;Di Domenico Antonio.;Dionisi Carlo.;Bini Cesare;Luci Claudio;Morodei Federico;Lacava Francesco;Safai Tehrani Francesco;Artoni Giacomo;Santi Lorenzo;Padovano Giovanni;Martinelli Luca;Maiani Luciano;Bauce Matteo;Gauzzi Paolo;Gentile Simonetta;Giagu Stefano;Ippolito Valerio
2023

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 a_{τ}. The dataset corresponds to an integrated luminosity of 1.44  nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=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 μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, 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 a_{τ} is -0.057<0.024.
2023
LHC; ATLAS; lead
01 Pubblicazione su rivista::01a Articolo in rivista
Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector / Betti, Alessandra; DE SALVO, Alessandro; Di Domenico, Antonio.; Dionisi, Carlo.; Bini, Cesare; Luci, Claudio; Morodei, Federico; Lacava, Francesco; SAFAI TEHRANI, Francesco; Artoni, Giacomo; Santi, Lorenzo; Padovano, Giovanni; Martinelli, Luca; Maiani, Luciano; Bauce, Matteo; Gauzzi, Paolo; Gentile, Simonetta; Giagu, Stefano; Ippolito, Valerio. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 131:15(2023), p. 151802. [10.1103/PhysRevLett.131.151802]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1694215
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