Prospects for detecting the couplings of axion-like particle with neutrinos at the CEPC

Abstract

We explore the possibility of detecting the couplings of axion-like particle (ALP) with leptons from their loop-level impact on the ALP couplings to electroweak (EW) gauge bosons via the signal process $e^+ e^- \to \gamma \gamma {E\mkern-10.5 mu/}$ at the Circular Electron Positron Collider (CEPC) and obtain prospective sensitivities to the ALP-lepton couplings. Our numerical results show that the CEPC with the center of mass energy $\sqrt{s}=240~(91)$ GeV and the integrated luminosity $\mathcal{L}=5.6~(16)$ ab$^{-1}$ might be sensitive for probing the ALP-lepton couplings in the ALP mass range from $10$ GeV to $130~(50)$ GeV, where the prospective sensitivities to the ALP-neutrino coupling $Tr(g_{a\nu\nu})/f_a$ can be as low as $0.016~(0.012)$ GeV$^{-1}$ and $0.0031~(2.8 \times 10^{-4})$ GeV$^{-1}$ for $c_{R}=0$ and $c_{R}=c_{L}$, and to the ALP-charged lepton coupling $Tr(g_{a\ell\ell})/f_a$ can be as low as $0.035~(0.07)$ GeV$^{-1}$ for $c_{L}=0$. We find that the prospective sensitivities given by the CEPC are not covered by the current and expected exclusion regions in some ALP mass intervals. The CEPC has the potential for exploring the ALP-neutrino couplings via some promising processes induced by the ALP-EW gauge boson couplings in the future.