Measurement of light-by-light scattering in ultra-peripheral Pb+Pb collisions with the ATLAS detector

In ultra-relativistic heavy-ion collisions, one expects copious rates of $\gamma\gamma$ processes through the interaction of the large electromagnetic fields of the nuclei which can lead to light-by-light scattering via loop diagrams. This process was directly observed for the first time in UPCs at the LHC by ATLAS. Final measurements of light-by-light scattering with full Run 2 dataset with substantially reduced uncertainties will be presented. This process provides a precise and unique opportunity to investigate extensions of the Standard Model such as axion-like particles.