Probing anomalous Couplings at a Future Muon Collider

We have studied anomalous four-photon couplings in the ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}\gamma \gamma {\mu }^{-}$ 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 ${g}_{1}=2.23×{10}^{-8}$ TeV$^{−4}$ and ${g}_{2}=4.22×{10}^{-8}$ 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.