2019/07/31 by G. David, Gabor David · 76 citations
Physics and Astronomy · #Astronomy #Atomic physics #Azimuth #Heavy ion #High-Energy Particle Collisions Research #Ion #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Photon #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #hep-ex #nucl-ex #nucl-th
paper · pdf · doi:10.1088/1361-6633/ab6f57
published in Reports on Progress in Physics 83(4), 046301 (IOP Publishing) · Invited review paper, small updates, version accepted and published in Reports on Progress in Physics April 2020 (reformatted and with added biography), Rept.Prog.Phys. 83 (2020) 4, 046301
openalex publication_date 2020/01/23 · arxiv created 2020/10/09 · arxiv updated 2020/10/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Direct real photons are arguably the most versatile tools to study relativistic heavy ion collisions. They are produced, by various mechanisms, during the entire space-time history of the strongly interacting system. Also, being colorless, most the time they escape without further interaction, i.e. they are penetrating probes. This makes them rich in information, but hard to decypher and interpret. This review presents the experimental and theoretical developments related to direct real photons since the 1970s, with a special emphasis on the recently emerged 'direct photon puzzle', the simultaneous presence of large yields and strong azimuthal asymmetries of photons in heavy ion collisions, an observation that so far eluded full and coherent explanation.