Probing $\tau$ lepton dipole moments at future Muon Colliders

TL;DR

This paper explores how future high-energy Muon Colliders can significantly improve measurements of the tau lepton's magnetic dipole moment, providing a sensitive probe for new physics beyond the Standard Model.

Contribution

It demonstrates the potential of Muon Colliders to measure tau g-2 with unprecedented precision, surpassing current experimental bounds.

Findings

Muon Colliders can probe tau g-2 at levels of 10^{-5} to 10^{-4}.

Processes like Drell-Yan and vector-boson-fusion are effective for this measurement.

The sensitivity achieved is orders of magnitude better than existing constraints.

Abstract

The anomalous magnetic moments of leptons represent excellent probes of the Standard Model and therefore also of possible new physics effects. In particular, the persisting hint of new physics in the muon $g$-2 motivates the investigation of similar effects also in the other leptonic dipoles. In this work, we examine the new physics sensitivity of the tau $g$-2 at future high-energy Muon Collider. We show that these facilities can access a number of processes like the Drell-Yan processes $\mu^+\mu^- \to \tau^+\tau^-(h)$, or vector-boson-fusion processes such as $\mu^+\mu^- \to \mu^+\mu^-\tau^+\tau^-$ and $\mu^+\mu^-\to \nu_\mu \bar{\nu}_\mu \tau^+\tau^-$ those can probe the tau $g$-2 at the level of $\mathcal{O}(10^{-5}-10^{-4})$, a resolution that is orders of magnitude better than the current bounds.