2019 July 07
Photon-photon fusion is a rare process at hadron and ion colliders. It is particularly interesting as a remarkably clean interaction with little (if any) remnant activity from the interacting particles. In this talk we present the status of photon-photon fusion measurements with the ATLAS detector. The observation of light-by-light scattering and the measurement of dimuon pairs in ultraperipheral Pb+Pb collisions are presented. The potential of axion-like particle searches with the upgraded ATLAS detector in Large Hadron Collider Runs~3 and~4 is reported. Intact protons from the photon-photon fusion process are scattered at small angles in diffractive and electromagnetic processes, and the protons are tagged by the ATLAS Forward Proton (AFP) detectors. These detectors can operate during standard high-luminosity LHC runs and collect data corresponding to a large integrated luminosity. The AFP detectors and their tracking performance during 2017 and 2018 operations are presented.