Axion-Like Particles at future $e^- p$ collider

TL;DR

This paper investigates the potential of the future LHeC collider to produce and constrain Axion-Like Particles (ALPs) across a wide mass range, using differential distribution analysis to set bounds on their couplings.

Contribution

It provides the first detailed analysis of ALP production at the LHeC, estimating cross sections and coupling limits for masses up to 300 GeV, highlighting the collider's sensitivity.

Findings

Upper bounds on ALP couplings are of order 10^{-1} for masses 5-300 GeV.

The LHeC can probe ALPs with higher mass and coupling sensitivity than some current experiments.

Differential distribution analysis effectively constrains ALP properties at future colliders.

Abstract

In this work, we explore the possibilities of producing Axion-Like Particles (ALPs) in a future $e^-p$ collider. Specifically, we focus on the proposed Large Hadron electron collider (LHeC), which can achieve a center-of-mass energy of $\sqrt{s} \approx 1.3$~TeV, enabling us to probe relatively high ALP masses with $m_a \lesssim 300$~GeV. The production of ALPs can occur through various channels, including $W^+W^-$, $\gamma\gamma$, $ZZ$, and $Z\gamma$-fusion within the collider environment. To investigate this, we conduct a comprehensive analysis that involves estimating the production cross section and constraining the limits on the associated couplings of ALPs, namely $g_{WW}$, $g_{\gamma\gamma}$, $g_{ZZ}$, and $g_{Z\gamma}$. To achieve this, we utilize a multiple-bin $\chi^2$ analysis on sensitive differential distributions. Through the analysis of these distributions, we determine upper bounds on the associated couplings within the mass range of 5~GeV $\leq m_a \leq$ 300~GeV. The obtained upper bounds are of the order of ${\cal O}(10^{-1})$ for $g_{\gamma\gamma}$ ($g_{WW}$, $g_{ZZ}$, $g_{Z\gamma}$) in $m_a \in$~[5, 200 (300)]~GeV considering an integrated luminosity of 1~ab$^{-1}$. Furthermore, we compare the results of our study with those obtained from other available experiments. We emphasize the limits obtained through our analysis and showcase the potential of the LHeC in probing the properties of ALPs.