Light-by-Light Scattering and Axion Like-Particle Searches in Pb+Pb Collisions at √sNN = 5:02 TeV in ATLAS Experiment at LHC

K. Maj, I. Grabowska-Bołd, ATLAS Collaboration
2021 Acta Physica Polonica. A  
The ultra-peripheral Pb+Pb collisions at √ sNN = 5.02 TeV recorded by 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 report summarises recent light-by-light measurements conducted using a combination of 2015 and 2018 Pb+Pb data sets collected by the ATLAS experiment, corresponding to an integrated luminosity of 2.2 nb −1 . The light-by-light event candidates are required to consist of only two
more » ... hotons produced exclusively, each with transverse energy ET > 2.5 GeV, pseudorapidity |η| < 2.4, diphoton invariant mass mγγ > 5 GeV, and with diphoton transverse momentum pT γγ < 1 GeV and acoplanarity below 0.01. The diphoton invariant mass distribution is used to set limits on the production of axion-like particles. topics: light-by-light scattering, axion-like particles, ATLAS
doi:10.12693/aphyspola.139.422 fatcat:nhvnyeopprh4xdyx36ky6dbbtq