Measurement of the γγ→ ττ cross section and constraints on the anomalous magnetic moment of the τ lepton in ultraperipheral PbPb collisions at √(sNN) = 5.02 TeV
Abstract
The production of τ lepton pairs via photon-photon fusion, γγ→ ττ, is studied in ultraperipheral lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset, collected by the CMS experiment in 2018, corresponds to an integrated luminosity of 1.70 nb−1. Four different τ+τ- decay final states are analyzed. A simultaneous likelihood fit to the measured lepton transverse momentum (pT) distributions, which incorporates information from both spectral shape and normalization, is used to constrain the anomalous magnetic moment of the τ lepton, aτ, and to extract the cross section of the process. The measured 95% CL interval for aτ is −0.039 lt aτ lt 0.032. The fiducial cross section, σγγ→ ττfid = 555+60−14 μb for tau leptons with pTτ gt 1 GeV and pseudorapidity lvertητrvert lt 3, is the most precise measurement for this process at the LHC to date and is in agreement with next-to-leading-order quantum electrodynamics predictions.
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BibTeX
@misc{collaboration2026measurement,
title = {{Measurement of the $γγ\to ττ$ cross section and constraints on the anomalous magnetic moment of the $τ$ lepton in ultraperipheral PbPb collisions at $\sqrts_\mathrmNN$ = 5.02 TeV}},
author = {CMS Collaboration},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.20148},
eprint = {2607.20148},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.20148},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Measurement of the γγ→ ττ cross section and constraints on the anomalous magnetic moment of the τ lepton in ultraperipheral PbPb collisions at √(s_NN) = 5.02 TeV
AU - CMS Collaboration
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2607.20148
UR - https://arxiv.org/abs/2607.20148
AB - The production of τ lepton pairs via photon-photon fusion, γγ→ ττ, is studied in ultraperipheral lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset, collected by the CMS experiment in 2018, corresponds to an integrated luminosity of 1.70 nb^−1. Four different τ^+τ^- decay final states are analyzed. A simultaneous likelihood fit to the measured lepton transverse momentum (p_T) distributions, which incorporates information from both spectral shape and normalization, is used to constrain the anomalous magnetic moment of the τ lepton, a_τ, and to extract the cross section of the process. The measured 95% CL interval for a_τ is −0.039 lt a_τ lt 0.032. The fiducial cross section, σ_γγ→ ττ^fid = 555^+60_−14 μb for tau leptons with p_T^τ gt 1 GeV and pseudorapidity lvertη^τrvert lt 3, is the most precise measurement for this process at the LHC to date and is in agreement with next-to-leading-order quantum electrodynamics predictions.
ER -