Institut de recherche sur les lois fondamentales de l'Univers

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of electromagnetism, and is forbidden by classical physics theories. Direct evidence for light-by-light scattering had proven elusive for decades, until the results from the LHC. We describe how these results have been obtained and what are the perspectives for the light-by-light scattering at the LHC and elsewhere and also beyond pure light-by-light scattering.