Spin effects in the tau-lepton pair induced by anomalous magnetic and electric dipole moments

TL;DR

This paper investigates how anomalous magnetic and electric dipole moments of the tau lepton influence tau-pair production and polarization at colliders, using extended Standard Model amplitudes in simulations.

Contribution

It introduces modifications to tau-pair production amplitudes incorporating tau dipole moments and demonstrates their effects on spin correlations and observables.

Findings

TauSpinner includes dipole moment effects in tau-pair production simulations.

Observable signatures of tau dipole moments are identified in collider processes.

Extensions to Standard Model amplitudes enable studying new physics contributions.

Abstract

The possible anomalous New Physics contributions to magnetic and electric dipole moments of the $\tau$ lepton have brought renewed interest in studying $\tau$-pair production at energies of the LHC and future colliders. We discuss effects of electromagnetic and weak dipole moment contributions to the $\tau$-lepton polarization and $\tau \tau$ spin correlations in the $\gamma\gamma \to \tau^-\tau^+$ and $q \bar{q} \to \tau^- \tau^+$ processes. Such processes have been observed in $pp$ and PbPb collisions in the LHC experiments. Extensions of the Standard Model amplitudes for $\gamma\gamma \to \tau^-\tau^+$ and $q \bar{q} \to \tau^- \tau^+$ processes, which include dipole moments of the $\tau$ lepton, are implemented in the TauSpinner Monte Carlo program. A few examples of signatures of $\tau \tau$ spin correlations and $\tau$-lepton dipole moments in observables are presented.