ALPs at Colliders

TL;DR

This paper establishes collider-based bounds on axion-like particles (ALPs) using mono-$\gamma$, tri-$\gamma$, and mono-jet searches, extending the search for heavier ALPs beyond traditional light axion constraints.

Contribution

It provides a model-independent analysis of collider bounds on ALPs and compares the effectiveness of different search channels, highlighting the potential of mono-jet searches.

Findings

Collider searches are complementary to existing bounds, probing heavier ALPs.

Mono-jet searches can effectively constrain ALP scenarios under certain model assumptions.

Collider bounds extend the accessible ALP parameter space beyond traditional limits.

Abstract

New pseudo-scalars, often called axion-like particles (ALPs), abound in model-building and are often associated with the breaking of a new symmetry. Traditional searches and indirect bounds are limited to light axions, typically in or below the KeV range for ALPs coupled to photons. We present collider bounds on ALPs from mono-$\gamma$, tri-$\gamma$ and mono-jet searches in a model independent fashion, as well as the prospects for the LHC and future machines. We find that they are complementary to existing searches, as they are sensitive to heavier ALPs and have the capability to cover an otherwise inaccessible region of parameter space. We also show that, assuming certain model dependent correlations between the ALP coupling to photons and gluons as well as considering the validity of the effective description of ALP interactions, mono-jet searches are in fact more suitable and effective in indirectly constraining ALP scenarios.