Sensitivity of the future $\boldsymbol{e^{-}p}$ collider to the coupling of axion-like particles with vector bosons

Abstract: Axion-like particles (ALPs) arise naturally in many extensions of the Standard Model (SM). We explore the discovery potential for ALPs of the Large Hadron electron Collider (LHeC) via the $W^{+}W^{-}$ fusion process. For concreteness, both cases of the ALP decaying to muon pairs and $b\overline{b}$ pairs are investigated. Our numerical results show that the LHeC with the center of mass energy of $1.3$ TeV and the integrated luminosity of $1$ ab$^{-1}$ might be more sensitive than the LHC in probing ALPs over a range of masses from a few tens of GeV to $900$ GeV, where the promising sensitivities to the coupling of ALP with $W^{\pm}$ bosons reach nearly $0.15$ TeV$^{-1}$ and $0.32$ TeV$^{-1}$ for the signal processes $e^{-}p\rightarrow\nu_{e}ja(a\rightarrow\mu^{+}\mu^{-})$ and $e^{-}p\rightarrow\nu_{e}ja(a\rightarrow b\overline{b})$, respectively.