2018/01/12 by Spencer R. Klein · 3 citations
Physics and Astronomy · #Astrophysics #Atomic physics #Hadron #High-Energy Particle Collisions Research #Invariant mass #Muon #Nuclear physics #Pair production #Particle physics #Particle physics theoretical and experimental studies #Photon #Physics #Production (economics) #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Star (game theory) #Virtual particle #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevc.97.054903
published as Phys. Rev. C 97, 054903 (2018) · 5 pages, 4 figures
arxiv created 2018/01/12 · openalex publication_date 2018/05/10 · arxiv updated 2018/05/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The STAR collaboration has observed an excess production of e+e^\ensuremath- pairs in relativistic heavy ion collisions, over the expectations from hadronic production models. The excess pairs have transverse momenta pT<150\phantom\rule4pt0exMeV/c and are most prominent in peripheral gold-gold and uranium-uranium collisions. The pairs exhibit a peak at the J/\ensuremathψ mass, but include a wide continuum, with pair invariant masses from 400\phantom\rule0.28em0exMeV/c2 up to 2.6\phantom\rule0.28em0exGeV/c2. The ALICE Collaboration observes a similar excess in peripheral lead-lead collisions, but only at the J/\ensuremathψ mass, without a corresponding continuum. This paper presents a calculation of the cross section and kinematic for two-photon production of e+e^\ensuremath- pairs, and find general agreement with the STAR data. The calculation is based on the starlight simulation code, which is based on the Weizs"acker-Williams virtual photon approach. The STAR continuum observations are compatible with two-photon production of e+e^\ensuremath- pairs. The ALICE analysis required individual muon pT be greater than 1 GeV/c; this eliminated almost all of the pairs from two-photon interactions, while leaving most of the J/\ensuremathψ decays.