Comprehensive Constraints on ALP Couplings from future $e^{+}{e}^{-}$ Colliders, Muon $g-2$, Thermal Dark Matter and Higgs Measurements

Abstract

In this article, we present projected 95\% C.L. limits on Axion-Like Particle (ALP) couplings from ALP production at a future $e^{+}{e}^{-}$ collider operating at $\sqrt{s}=250\text{GeV}$ with integrated luminosity $L=0.5{\text{ab}}^{-1}$. We constrain the effective couplings $g_{{\hat{I}}^3{\hat{I}}^3}$, $g_{Z{\hat{I}}^3}$, $g_{ZZ}$, and $g_{WW}$ over the ALP mass range $20\text{GeV}\le m_a\le 100\text{GeV}$, finding projected bounds at the level of $\mathcal{O}(10^{-1}){\text{TeV}}^{-1}$ for $g_{{\hat{I}}^3{\hat{I}}^3}/f_a$. Given that the latest muon anomalous magnetic moment measurement ($\hat{I}”a_{\hat{I}}¼$) shows no statistically significant deviation from the Standard Model prediction, we reinterpret the ALP contributions to $\hat{I}”a_{\hat{I}}¼$ as a stringent consistency requirement. We then derive the corresponding allowed regions for $g_{{\hat{I}}^3{\hat{I}}^3}$ and the ALP--muon coupling $C_{\hat{I}¼\hat{I}¼}$, and apply them to a fermionic dark matter scenario in which the relic density depends on both the dark matter mass $m_{\ddot{I}}‡$ and $m_a$. The same parameter space is further constrained by Higgs signal strength measurements through $h\to {\hat{I}}^3{\hat{I}}^3$ and $h\to Z{\hat{I}}^3$. A comparative analysis with existing experimental and theoretical bounds highlights the complementarity of $\hat{I}”a_{\hat{I}}¼$, dark matter, and Higgs observables in restricting ALP couplings, demonstrating that even in the absence of a $\hat{I}”a_{\hat{I}}¼$ anomaly, these constraints provide essential guidance for viable ALP parameter space.

9 pages, 6 figures, Version accepted for publication in the European Physical Journal C