Probing MeV to 90 GeV axion-like particles with LEP and LHC

TL;DR

This paper investigates constraints on axion-like particles in the MeV to 90 GeV range using LEP data and explores the potential of LHC and future colliders to detect such particles, filling a sensitivity gap in this mass range.

Contribution

It demonstrates that LEP data constrains ALPs in the MeV to 90 GeV range and analyzes the LHC's promising search channels for these particles.

Findings

LEP data constrains ALPs up to the Z mass.

LHC can search for ALPs in the 4-60 GeV range via the $pp \to 3\gamma$ channel.

Future colliders could improve sensitivity to ALPs.

Abstract

Axion-like particles (ALPs), relatively light (pseudo-)scalars coupled to two gauge bosons, are a common feature of many extensions of the Standard Model. Up to now there has been a gap in the sensitivity to such particles in the MeV to 10 GeV range. In this note we show that LEP data on $Z\to\gamma\gamma$ decays provides significant constraints in this range (and indeed up to the $Z$-mass). We also discuss the sensitivities of LHC and future colliders. Particularly the LHC shows promising sensitivity in searching for a pseudo-scalar with $4 \lesssim m_a \lesssim 60$ GeV in the channel $pp \to 3 \gamma$ with $m_{3\gamma}\approx m_{Z}$.