2019/09/05 by Sebastian Lehner, Lehner, Sebastian
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.1909.02508
Dielectrons probe a wide range of phenomena in heavy-ion collisions. These\ninclude light- and heavy-flavour meson production, thermal radiation and\ncoherent photo-production. The latter process is distinguished by dielectron\nproduction at low transverse-pair momentum ( itp_ textrmT,ee).\nTransverse momentum spectra of dielectrons in central and peripheral Pb-Pb\ncollisions are extracted and compared to the corresponding expectations. In\ncentral collisions the data fit the expected spectrum, which is dominated by\nsemi-leptonic decays of correlated heavy-flavour hadrons. In peripheral\ncollisions, the data exhibit an excess at low ptee with respect to hadronic\nand thermal sources. The observed excess yield is compatible with calculations\nfor dielectron production from coherent photon-photon interactions.\n