Searches for axion-like particles via ${\hat{I}}^3{\hat{I}}^3$ fusion at future ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ colliders

Abstract

Opportunities for searches for axion-like particles (ALPs) coupling to photons in ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ collisions at the Future Circular Collider (FCC-ee) and International Linear Collider (ILC) are investigated. We perform a study of the photon-fusion production of ALPs decaying into two photons, ${\mathrm{e}}^{+}{\mathrm{e}}^{-}\stackrel{{\hat{I}}^3{\hat{I}}^3}{⟶}{\mathrm{e}}^{+}a({\hat{I}}^3{\hat{I}}^3){\mathrm{e}}^{-}$, over the light-by-light continuum background, for the planned FCC-ee and ILC center-of-mass energies and integrated luminosities. An analysis of the feasibility measurements is presented using parametrized simulations for two types of detectors. Upper limits at 95% confidence level (CL) on the cross section for ALP production, $\ddot{I}ƒ({\hat{I}}^3{\hat{I}}^3\to a\to {\hat{I}}^3{\hat{I}}^3)$, and on the ALP-photon coupling are obtained over the $m_a\approx 0.1$--1000 GeV ALP mass range, and compared to current and future collider searches. Production cross sections down to $\ddot{I}ƒ({\hat{I}}^3{\hat{I}}^3\to a\to {\hat{I}}^3{\hat{I}}^3)\approx 1$ fb (1 ab) will be probed at $m_a\approx 1$ (300) GeV, corresponding to constraints on the axion-photon coupling as low as $g_{\mathrm{a}{\hat{\mathrm{I}}}^3{\hat{\mathrm{I}}}^3}\approx 2\cdot 10^{-3}$ TeV${}^{-1}$.

this version is published in PRD