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Observation of γγ→ττ in proton–proton collisions and limits on the anomalous electromagnetic moments of the τ lepton.

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Title: Observation of γγ→ττ in proton–proton collisions and limits on the anomalous electromagnetic moments of the τ lepton.
Authors: CMS Collaboration, The1 (AUTHOR) cms-publication-committee-chair@cern.ch
Source: Reports on Progress in Physics. Oct2024, Vol. 87 Issue 10, p1-21. 21p.
Subjects: Electric dipole moments, Standard model (Nuclear physics), Magnetic moments, Standard deviations, Data recorders & recording, Proton-proton interactions
Abstract: The production of a pair of τ leptons via photon–photon fusion, γ γ → τ τ , is observed for the first time in proton–proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. Events with a pair of τ leptons produced via photon–photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section of γ γ → τ τ is σ obs fid = 12.4 − 3.1 + 3.8 fb . Constraints are set on the contributions to the anomalous magnetic moment ( a τ ) and electric dipole moments ( d τ ) of the τ lepton originating from potential effects of new physics on the γ τ τ vertex: a τ = 0.0009 − 0.0031 + 0.0032 and | d τ | < 2.9 × 10 − 17 e cm (95% confidence level), consistent with the standard model. [ABSTRACT FROM AUTHOR]
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Abstract:The production of a pair of τ leptons via photon–photon fusion, γ γ → τ τ , is observed for the first time in proton–proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. Events with a pair of τ leptons produced via photon–photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section of γ γ → τ τ is σ obs fid = 12.4 − 3.1 + 3.8 fb . Constraints are set on the contributions to the anomalous magnetic moment ( a τ ) and electric dipole moments ( d τ ) of the τ lepton originating from potential effects of new physics on the γ τ τ vertex: a τ = 0.0009 − 0.0031 + 0.0032 and | d τ | < 2.9 × 10 − 17 e cm (95% confidence level), consistent with the standard model. [ABSTRACT FROM AUTHOR]
ISSN:00344885
DOI:10.1088/1361-6633/ad6fcb