Light-by-Light Scattering at the LHC and the search for Axion Like Particles

Light-by-light scattering is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics and was predicted already more than 70 years ago by Heisenberg and Euler. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultrarelativistic colliding lead ions. Using 480 μb−1 of lead–lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, a first evidence for light-by-light scattering in collisions was found. In this talk, I review the experimental setup and the corresponding data-analysis with a special focus on potential systematic and theoretical uncertainties. Moreover, I will give an outlook on possible searches for axion like particles using this reaction as well as in protonproton collisions in general.