Probing axion-like particles at the Electron-Ion Collider

The Electron-Ion Collider (EIC), a forthcoming powerful high-luminosity facility, represents an exciting opportunity to explore new physics. In this article, we study the potential of the EIC to probe the coupling between axion-like particles (ALPs) and photons in coherent scattering. The ALPs can be produced via photon fusion and decay back to two photons inside the EIC detector. In a prompt-decay search, we find that the EIC can set the most stringent bound for m(a) less than or similar to 20 GeV and probe the effective scales Lambda less than or similar to 10(5) GeV. In a displaced-vertex search, which requires adopting an EM calorimeter technology that provides directionality, the EIC could probe ALPs with m(a) less than or similar to 1 GeV at effective scales Lambda less than or similar to 10(7) GeV. Combining the two search strategies, the EIC can probe a significant portion of unexplored parameter space in the 0.2 < m(a) < 20 GeV mass range.