Speaker
Description
Ultra-peripheral collisions (UPC) involve collisions at impact parameters large enough, such that there are no hadronic interactions - ions interact only electromagnetically, either via photonuclear or two-photon interactions. UPCs of heavy ions at the LHC are the energy frontier for electromagnetic interactions. They provide a unique opportunity to study various physics phenomena from a precision test of quantum electrodynamics and quantum chromodynamics, to the search for new physics beyond the standard model. In the presented study, we briefly introduce the electrodynamics of the underlying photon-photon process, relying on equivalent photon approximation, followed by an overview of b-jet tagging algorithms. Their performance is evaluated using b-tagging efficiency and light jet rejection, first for low-level taggers based on jet topology (IP3D, SV1) and up to the state of art deep neural networks (DL1r). Jets are reconstructed from ATLAS detector response to energy depositions in its tracker and calorimeter. To arrive at the true particle-level energy, we analyze the jet energy scale and its corrections for a better understanding of the systematic uncertainty of our sample data.
