Speaker
Description
Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons, leading to multiple photon-induced processes. This talk presents a series of measurements of such processes performed by the ATLAS Collaboration. New measurements of exclusive dilepton production (electron, muon, and tau pairs) are discussed. Furthermore, the tau-pair production measurements can constrain the tau lepton's anomalous magnetic dipole moment. High statistics measurements of light-by-light scattering shown in this talk provide a precise and unique opportunity to investigate extensions of the Standard Model, such as the presence of axion-like particles. Presented measurements of muon pairs produced via two-photon scattering processes in hadronic Pb+Pb collisions provide a novel test of strong-field QED and can be a potentially sensitive electromagnetic probe of the quark-gluon plasma. These include the dependence of the cross-section and angular correlation on the mean-$\p_{\mathrm{T}}$ of the dimuon pair, the rapidity separation between the muons, and the angle that the pair makes with the second-order event-plane. Presented results are further compared with recent theory calculations.
