Axionlike particle search at Higgs factories
Kingman Cheung, C. J. Ouseph
Abstract
We study the potential of the future Higgs factories, including the ILC, CEPC, and FCC-ee with $\sqrt{s}=240--250\text{ }\text{ }\mathrm{GeV}$ on discovering axionlike particles (ALPs) through various production channels in the leptonic final states, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}f\overline{f}a$, where $f=e$, $\ensuremath{\mu}$, $\ensuremath{\nu}$. We show that the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}a$ with $a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ provides the best bounds for the ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ and ${g}_{aZZ}$ couplings, while ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}}a$, with $a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ offers the best bounds for the ${g}_{aZZ}$ and ${g}_{aZ\ensuremath{\gamma}}$ couplings. The ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}a$ with $a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ provides intermediate sensitivity to the ${g}_{aZZ}$ coupling. Our estimates of the bounds for the ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$, ${g}_{aZ\ensuremath{\gamma}}$, and ${g}_{aZZ}$ couplings as a function of ALP mass (${M}_{a}$) ranging from 0.1 to 100 GeV provide valuable insights for future experiments aiming to detect ALPs. We find that ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ around $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ for ${M}_{a}=0.1--6\text{ }\text{ }\mathrm{GeV}$ is currently not ruled out by any other experiments.