Axion Like Particle Search at Higgs Factories

Abstract

We study the potential of the future Higgs factories, including the ILC, CEPC, and FCC-ee with $\sqrt{s}$ = 240-250 GeV on discovering axion-like particles (ALPs) through various production channels in the leptonic final states, $e^{+}{e}^{-}\to f\bar{f}a$, where $f=e,\mu ,\nu$. We show that the $e^{+}{e}^{-}\to e^{+}{e}^{-}a$ with $a\to \gamma \gamma$ provides the best bounds for the $g_{a\gamma \gamma }$ and $g_{aZZ}$ couplings, while $e^{+}{e}^{-}\to \nu \bar{\nu }a$, with $a\to \gamma \gamma$ offers the best bounds for the $g_{aZZ}$ and $g_{aZ\gamma }$ couplings. The $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}a$ with $a\to \gamma \gamma$ provides intermediate sensitivity to the $g_{aZZ}$ coupling. Our estimates of the bounds for the $g_{a\gamma \gamma }$, $g_{aZ\gamma }$, and $g_{aZZ}$ couplings as a function of ALP mass ($M_a$) ranging from 0.1 GeV to 100 GeV provide valuable insights for future experiments aiming to detect ALPs. We find that $g_{a\gamma \gamma }$ around $1.5\times 10^{-4}\mathrm{Ge}{\mathrm{V}}^{-1}$ for $M_a=0.1-6$ GeV is currently not ruled out by any other experiments.

Comments: 20 pages, 8 figures