Probing axion-like particles at the Electron-Ion Collider

Abstract

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 <jats:italic>m</jats:italic><jats:sub><jats:italic>a</jats:italic></jats:sub> ≲ 20 GeV and probe the effective scales Λ ≲ 10<jats:sup>5</jats:sup> GeV. In a displaced-vertex search, which requires adopting an EM calorimeter technology that provides directionality, the EIC could probe ALPs with <jats:italic>m</jats:italic><jats:sub><jats:italic>a</jats:italic></jats:sub> ≲ 1 GeV at effective scales Λ ≲ 10<jats:sup>7</jats:sup> GeV. Combining the two search strategies, the EIC can probe a significant portion of unexplored parameter space in the 0.2 &lt; <jats:italic>m</jats:italic><jats:sub><jats:italic>a</jats:italic></jats:sub> &lt; 20 GeV mass range.