Omar Morozi Search for an axion-like particle with forward proton scattering in association with photon pairs at ATLAS [ATLAS Collaboration] Hide abstract | Show figures | Show BibTeX | Show discussion | View PDF | 2304.10953v1 A search for forward proton scattering in association with light-by-light scattering mediated by an axion-like particle is presented, using the ATLAS Forward Proton spectrometer to detect scattered protons and the central ATLAS detector to detect pairs of outgoing photons. Proton-proton collision data recorded in 2017 at a centre-of-mass energy of s√=13 TeV were analysed, corresponding to an integrated luminosity of 14.6 fb−1. A total of 441 candidate signal events were selected. A search was made for a narrow resonance in the diphoton mass distribution, corresponding to an axion-like particle (ALP) with mass in the range 150-1600 GeV. No excess is observed above a smooth background. Upper limits on the production cross section of a narrow resonance are set as a function of the mass, and are interpreted as upper limits on the ALP production coupling constant, assuming 100% decay branching ratio into a photon pair. The inferred upper limit on the coupling constant is in the range 0.04-0.09 TeV−1 at 95%confidence level. Authors' comments: 35 pages in total, author list starting page 18, 8 figures, 1 tables, submitted to JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2019-28/