Detecting the coupling of axion-like particles with fermions at the ILC

Abstract

New pseudoscalars, axion-like particles (ALPs), provide the exciting target for present and future collider-based experiments. Search for ALPs is performed in this paper via the $W^{+}W^{-}$ fusion process $e^{-}e^{+}\rightarrow\nu_{e}\overline{\nu_{e}}a\rightarrow\nu_{e}\overline{\nu_{e}}f\overline{f}$ at the $1$ TeV ILC corresponding to an integrated luminosity of $1$ ab$^{-1}$ and the beam polarization $P(e^{-}$, $e^{+}) = (-80\%$, $+20\%)$. Owing to the good capability of the ILC in performing b-tagging and the sufficiently large branching ratio of the ALP decaying into a pair of b quarks, the decay channel $a\rightarrow{b\overline{b}}$ is mainly concerned. The prospective sensitivities provided by the ILC on the ALP-fermion coupling as low as $1$ TeV$^{-1}$ and $1.75$ TeV$^{-1}$ are derived at $95\%$ confidence level in the ALP mass intervals $37-50$ GeV and $52-300$ GeV, respectively. Our results will help to probe significant parameter space in an unexplored region beyond the existing constraints.