Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

Summary, in English

The PHENIX collaboration presents first measurements of low-momentum (0.41 GeV/c) direct-photon yield dNγdir/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high pT (>5 GeV/c), but when results from different collision energies are compared, an additional sNN-dependent multiplicative factor is needed to describe the integrated-direct-photon yield. © 2019 authors. Published by the American Physical Society.

• Author: A. Adare; Peter Christiansen; Hans-Åke Gustafsson; Eva Haslum; Joakim Nystrand; Anders Oskarsson; Ingvar Otterlund; Sarah Rosendahl; David Silvermyr; Evert Stenlund; Henrik Tydesjö; L. Zou
• Department/s: eSSENCE: The e-Science Collaboration; Particle and nuclear physics
• Publishing year: 2019-07-10
• Language: English
• Publication/Series: Physical Review Letters
• Volume: 123
• Issue: 2
• Links: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069921283&doi=10.1103%2fPhysRevLett.123.022301&partnerID=40&md5=8bb199c6b6c3e1722b1bc416abb104d3; http://dx.doi.org/10.1103/PhysRevLett.123.022301
• Document type: Journal article
• Publisher: American Physical Society
• Topic: Subatomic Physics
• Keywords: Heavy ions; Photons; Au+Au collisions; Collision energies; Collision systems; Large Hadron Collider; Multiplicative factors; Relativistic Heavy Ion Collider; Scaling behavior; Ultrarelativistic heavy ion collision; Colliding beam accelerators
• Status: Published
• ISBN/ISSN/Other: ISSN: 1079-7114