The sensitivity to BSM in di-taon production at the LHC

TL;DR

This paper explores how ultraperipheral Pb+Pb collisions at the LHC can improve measurements of the tau lepton's anomalous magnetic moment and electric dipole moment, potentially surpassing current experimental limits.

Contribution

It provides new sensitivity estimates for tau lepton dipole moments using LHC heavy-ion collision data, with potential improvements over existing bounds.

Findings

Expected limits on $a_\tau$ are twice as good as current best limits.

Potential to improve limits by a factor of two at High Luminosity LHC.

Results for $d_\tau$ are competitive with Belle experiment bounds.

Abstract

We discuss the sensitivity of the $\gamma\gamma \to \tau^+\tau^-$ process in ultraperipheral Pb+Pb collisions at LHC energies on the anomalous magnetic moment of $\tau$ lepton ($a_\tau$). We derive the corresponding cross sections considering semi-leptonic decays of both leptons in the fiducial volume of ATLAS and CMS detectors. The expected limits on $a_\tau$ with the existing Pb+Pb dataset are found to be better by a factor of two comparing to current best experimental limits and can be further improved by another factor of two at High Luminosity LHC. In addition, our results for tau lepton electric dipole moment, $d_\tau$, can be competitive with the current best limits that were obtained by the Belle experiment.