Probing anomalous $\gamma\gamma\gamma\gamma$ couplings at a future muon collider

TL;DR

This study investigates the potential to detect anomalous four-photon couplings at future high-energy muon colliders, providing bounds and unitarity constraints across various collision energies.

Contribution

It offers the first detailed analysis of anomalous four-photon couplings at muon colliders, including cross section calculations, exclusion bounds, and unitarity checks at multiple energies.

Findings

95% C.L. bounds on couplings at 100 TeV collision energy

Unitarity is preserved within the obtained coupling bounds

Cross sections increase with collision energy and photon invariant mass

Abstract

We have studied anomalous four-photon couplings in the $\mu^+\mu^- \rightarrow \mu^+ \gamma\gamma \mu^-$ scattering at a future muon collider. The collision energies of 3 TeV, 14 TeV, and 100 TeV are addressed. Both differential and total cross sections versus invariant mass of the outgoing photons are calculated. The best 95\% C.L. exclusion bounds on anomalous couplings are obtained to be $g_1 = 2.23 \times 10^{-8}$ TeV$^{-4}$ and $g_2 = 4.22 \times 10^{-8}$ TeV$^{-4}$. They correspond to the muon collision energy of 100 TeV. The partial-wave unitary constraints on $g_1$ and $g_2$ are examined. We have demonstrated that the unitarity is not violated in a region of the anomalous couplings obtained in the present paper.