Observation of $\tau$ lepton pair production in ultraperipheral lead-lead collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

CMS Collaboration

Preprint

PUBDB-2022-04494

Observation of $\tau$ lepton pair production in ultraperipheral lead-lead collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

CMS Collaboration (Collaboration author)DESY*

2022

[10.3204/PUBDB-2022-04494]

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Please use a persistent id in citations: doi:10.3204/PUBDB-2022-04494

Report No.: CERN-EP-2022-098; CMS-HIN-21-009; arXiv:2206.05192

Abstract: We present an observation of photon-photon production of $\tau$ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 $\mu$b$^{-1}$ collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The $\gamma\gamma\to\tau^+\tau^-$ process is observed for $\tau\tau$ events with a muon and three charged hadrons in the final state. The measured fiducial cross section is $\sigma(\gamma\gamma\to\tau^+\tau^-)$ = 4.8$\pm$ 0.6 (stat) $\pm$ 0.5 (syst) $\mu$b, in agreement with leading-order QED predictions. Using $\sigma(\gamma\gamma\to\tau^+\tau^-)$, we estimate a model-dependent value of the anomalous magnetic moment of the $\tau$ lepton of $a_\tau$ = 0.001$^{+0.055}_{-0.089}$ at a 68% confidence level.

Keyword(s): higher-order: 0 ; lepton: pair production ; peripheral ; muon ; quantum electrodynamics ; magnetic moment ; CMS ; experimental results ; photon photon --> tau+ tau- ; 5020 GeV-cms/nucleon

Note: Submitted to Physical Review Letters. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-21-009 (CMS Public Pages)

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