Photon interactions in ultra-peripheral heavy-ion collisions in the ATLAS detector at the LHC

Authors

DOI:

https://doi.org/10.23727/CERN-Proceedings-2018-001.137

Keywords:

CERN report, PHOTON2017, photon-photon collisions, photon-lead colli- sions, light-by-light scattering, heavy-ion collisions, LHC, ATLAS

Abstract

Two analyses involving photon interactions in ultra-peripheral lead-lead collisions in the ATLAS detector at the LHC are described, namely the study of dijet production in photo-nuclear ultra-peripheral collisions and a measurement of light-by-light scattering. The first, is an important way to probe and constrain nuclear parton distribution functions, which are known to exhibit suppression at low Bjorken-x with respect to proton PDFs, as well as enhancement at higher Bjorken-x. Light-by-light scattering is forbidden in classical electrodynamics as it violates the super-position principle and is a fundamental prediction of quantum mechanics. The first direct evidence for this interaction with two quasi-real initial state photons is presented.

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Published

2018-12-20

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Section

Photon-hadron collisions at hadron colliders