Speaker
Description
Light-by-light (LbyL) scattering, $\gamma\gamma\rightarrow\gamma\gamma$, is a very rare process allowed in Quantum Electrodynamics via a loop diagram. The precise measurement of this process is potentially sensitive to contributions from Beyond Standard Model. Despite the small cross-section, the LbyL scattering can be observed in ultra-peripheral high energy heavy-ion collisions due to strong electromagnetic fields accompanying the lead beam. In this talk we discuss the first direct observation of LbyL scattering established by ATLAS Collaboration using 2018 Pb+Pb dataset. We also summarize other new measurements done using ultra-peripheral events such as the measurement of multi-particle correlations and measurement of di-muon production.
