Probing the τ anomalous magnetic and electric dipole moments in photon-induced γγ→τ+τ- production at the FCC-hh
Abstract
The sensitivity of the FCC-hh to the anomalous magnetic moment aτ and the electric dipole moment dτ of the τ lepton is studied in photon-induced γγ→τ+τ- production with both τ leptons decaying hadronically. Central exclusive (elastic) signal events, in which both protons remain intact, are generated with MadGraph5_aMC@NLO using a FeynRules UFO model of the anomalous γττ vertex merged with the TauDecay model, so that the τ decays and their spin correlations are included in the matrix element. Single- and double-dissociative production is estimated with SuperChic and added to the elastic signal with its own coupling dependence and with normalisation and shape uncertainties of 25%. Pythia 8 decays the unstable hadrons in the signal, decays the τ leptons and simulates the parton shower and hadronisation in the backgrounds, and hadronises the dissociated protons. Signal and backgrounds are passed through the Delphes simulation of the FCC-hh detector. Hadronic τ decays are reconstructed from particle-flow tracks and photons with an algorithm based on the hadrons-plus-strips approach, with an efficiency of 73.4% within the acceptance. Requiring no additional tracks from the τ vertices retains part of the dissociative contribution and reduces the Drell-Yan and γγ→ WW backgrounds to 0.9% of the SM yield. The couplings are constrained from the shape of the total transverse mass distribution. For a centre-of-mass energy of 84 TeV and 30 ab−1, the expected 95% CL limits are −3.38×10−4 < aτ< 3.36×10−4 and |dτ| < 1.88×10−18 ecm, about an order of magnitude beyond the current bounds. Results are also given for FCC-hh scenarios between 72 and 120 TeV and for an optimistic detector parametrisation.
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BibTeX
@misc{senol2026probing,
title = {{Probing the $τ$ anomalous magnetic and electric dipole moments in photon-induced $γγ\toτ^+τ^-$ production at the FCC-hh}},
author = {A. Senol and H. Denizli and M. Köksal},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28147},
eprint = {2610.28147},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28147},
}
RIS
TY - UNPB
TI - Probing the τ anomalous magnetic and electric dipole moments in photon-induced γγ→τ^+τ^- production at the FCC-hh
AU - A. Senol
AU - H. Denizli
AU - M. Köksal
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28147
UR - https://arxiv.org/abs/2610.28147
AB - The sensitivity of the FCC-hh to the anomalous magnetic moment a_τ and the electric dipole moment d_τ of the τ lepton is studied in photon-induced γγ→τ^+τ^- production with both τ leptons decaying hadronically. Central exclusive (elastic) signal events, in which both protons remain intact, are generated with MadGraph5_aMC@NLO using a FeynRules UFO model of the anomalous γττ vertex merged with the TauDecay model, so that the τ decays and their spin correlations are included in the matrix element. Single- and double-dissociative production is estimated with SuperChic and added to the elastic signal with its own coupling dependence and with normalisation and shape uncertainties of 25%. Pythia 8 decays the unstable hadrons in the signal, decays the τ leptons and simulates the parton shower and hadronisation in the backgrounds, and hadronises the dissociated protons. Signal and backgrounds are passed through the Delphes simulation of the FCC-hh detector. Hadronic τ decays are reconstructed from particle-flow tracks and photons with an algorithm based on the hadrons-plus-strips approach, with an efficiency of 73.4% within the acceptance. Requiring no additional tracks from the τ vertices retains part of the dissociative contribution and reduces the Drell-Yan and γγ→ WW backgrounds to 0.9% of the SM yield. The couplings are constrained from the shape of the total transverse mass distribution. For a centre-of-mass energy of 84 TeV and 30 ab^−1, the expected 95% CL limits are −3.38×10^−4 < a_τ< 3.36×10^−4 and |d_τ| < 1.88×10^−18 ecm, about an order of magnitude beyond the current bounds. Results are also given for FCC-hh scenarios between 72 and 120 TeV and for an optimistic detector parametrisation.
ER -