Axion-Like Particles at High Energy Muon Colliders -- A White paper for Snowmass 2021

Abstract

We study the discovery potential for heavy axion-like particles (ALPs) and the perspectives for determining their coupling properties at a muon collider. Focusing on their couplings to the Standard Model (SM) gauge bosons ${\hat{I}}^3,Z,W^{\pm }$, we show that a high-energy muon collider can substantially extend the mass coverage, essentially reaching the kinematic limit of the collider energy. The unique kinematics allow for non-ambiguous determination of the individual coupling strengths. The associated production via $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ annihilation and the VBF processes with the tagged outgoing muons can be utilized to verify the CP property of the ALPs. We illustrate our results for a muon collider running at 3 TeV and 10 TeV.

16 pages, 4 figures. Contribution to Snowmass 2021