Abstract:
The ultra-peripheral Pb+Pb collisions at √𝑠NN =5.02 TeV recorded at the ATLAS experiment are used to study a rare light-by-light scattering process, 𝛾𝛾→𝛾𝛾, allowed in Quantum Electrodynamics via a loop diagram. The talk summarises light-by-light measurements conducted using a combination of 2015 and 2018 datasets recorded by the ATLAS experiment, corresponding to an integrated luminosity of 2.2 n𝑏−1. The differential distributions, presented as functions of kinematic and angular variables of the final-state photons, are unfolded for detector effects. The fiducial and differential cross-sections are presented and compared with theoretical predictions. The diphoton invariant mass distribution is used to set limits on the production of axion-like particles. This result provides the most stringent limits to date on axion-like particle production for masses in the range 6-100 GeV.
Important: This seminar is remote only due to the COVID-19 regulations