Probing Muon $g-2$ at a Future Muon Collider

TL;DR

This paper explores how a future multi-TeV muon collider could effectively test beyond Standard Model physics related to the muon g-2 anomaly by analyzing SMEFT parameters across multiple energies.

Contribution

It demonstrates the advantage of multi-energy muon collider data and interference effects in constraining SMEFT coefficients related to the muon g-2 discrepancy.

Findings

Multi-energy runs improve SMEFT constraints.

Interference effects are crucial for accurate analysis.

Lower energy, high-statistics runs can outperform single high-energy runs.

Abstract

The $4.2\sigma$ discrepancy in the $(g-2)$ of the muon provides a hint that may indicate that physics beyond the standard model is at play. A multi-TeV scale muon collider provides a natural testing ground for this physics. In this paper, we discuss the potential to probe the BSM parameter space that is consistent with solving the $(g-2)_{\mu}$ discrepancy in the language of the SMEFT, utilizing the statistical power provided by fitting event rates collected running at multiple energies. Our results indicate the importance of including interference between the BSM and the SM amplitudes, and illustrates how a muon collider running at a handful of lower energies and with less total collected luminosity can better significantly constrain the space of relevant SMEFT coefficients than would be possible for a single high energy run.