Searching for Strangeness Enhancement in Ultra-Peripheral Pb+Pb Collisions with ATLAS

Strangeness enhancement is considered a signature of the formation of a quark-gluon plasma and has thus been studied in various collisions involving different particle species. This study investigates the feasibility of measuring strange hadrons in photonuclear ultra-peripheral collisions using 5.02 TeV Pb+Pb collision data collected by the ATLAS experiment at CERN's Large Hadron Collider. γ+Pb collisions have recently been found to exhibit collective phenomena similar to that of a QGP. Hence, it is natural to search for strangeness enhancement as well. By fitting distributions of the energy lost by low-momentum reconstructed charged particle tracks as they traverse ATLAS's Pixel Detector (dE/dx), the yields of identified pions, kaons, and protons can be extracted. We explore the identified charged-particle yields as a function of charged-particle multiplicity, along with the ratio of identified kaons to pions, and compare with Monte Carlo simulations of γ+Pb collisions. Additionally, we seek to compare the charged-particle multiplicity dependence of the kaon-to-pion ratio in γ+Pb collisions to that in peripheral Pb+Pb collisions, where strangeness enhancement is expected.