Searching for axion-like particles with proton tagging at the LHC

TL;DR

This paper proposes a method to search for axion-like particles at the LHC by detecting photon pairs with proton tagging, providing competitive bounds for masses above 600 GeV.

Contribution

It introduces a novel search strategy using proton tagging in central exclusive production to constrain ALP-photon couplings at high masses.

Findings

Expected bounds on ALP-photon coupling are competitive for masses 600 GeV to 2 TeV.

The method is effective for both CP-odd and CP-even scalars.

Search efficiency is independent of the ALP width.

Abstract

The existence of an axion-like particle (ALP) would induce anomalous scattering of light by light. This process can be probed at the Large Hadron Collider in central exclusive production of photon pairs in proton-proton collisions by tagging the surviving protons using forward proton detectors. Using a detailed simulation, we estimate the expected bounds on the ALP--photon coupling for a wide range of masses. We show that the proposed search is competitive and complementary to other collider bounds for masses above 600 GeV, especially for resonant ALP production between 600 GeV and 2 TeV. Our results are also valid for a CP-even scalar, and the efficiency of the search is independent of the width of the ALP.