Transverse flow effects on high-energy photons emitted by expanding quark-gluon plasma

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.48.1117· OSTI ID:7369086

Alam, J ^[1]; Srivastava, D K ^[2]; Sinha, B; Basu, D N ^[1]

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1. Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Calcutta 700 064 (India)
2. Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Calcutta 700 064 (India) Theoretical Physics Institute, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

High-energy photons emitted in ultrarelativistic nucleus-nucleus collisions at energies reached at the CERN SPS and LHC and the BNL RHIC are discussed as a source of information on the collision dynamics and as a signature of the deconfining phase transition. The energy density and velocity fields of the expanding matter have been computed assuming cylindrical symmetry along the transverse direction and boost invariance along the longitudinal direction. The emission of photons from an expanding quark-gluon plasma undergoing a first-order phase transition has been evaluated. When the transverse flow of the system is accounted for, it is found that the photons having their origin in the hadronic matter are comparable to those originating in the quark-gluon plasma for [ital p][sub [ital T]] greater than 2 GeV, at energies reached at the SPS and RHIC. At energies reached at the LHC, photons having a [ital p][sub [ital T]] larger than about 4 GeV are shown to have their origin predominantly in the quark-gluon plasma. The location of the [ital p][sub [ital T]] window is shown to be very sensitive to the value of the freeze-out temperature chosen. The feasibility of evaluating the direct (QCD) photons has been studied. Photons fragmented off final state quarks in parton-parton scattering are shown to provide the largest background beyond [ital p][sub [ital T]][approx]3 GeV at energies reached at the LHC. Accounting for hadronic degrees of freedom beyond the pion is found to be important.

• DOE Contract Number: FG02-85ER40238
• OSTI ID: 7369086
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 48:3; ISSN 0556-2821; ISSN PRVDAQ
• Country of Publication: United States
• Language: English

Related Subjects

662230 -- Quantum Chromodynamics-- (1992-)
663450* -- Heavy-Ion-Induced Reactions & Scattering-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CHARGED-PARTICLE REACTIONS
DEEP INELASTIC HEAVY ION REACTIONS
EMISSION
ENERGY DENSITY
ENERGY RANGE
FIELD THEORIES
FRAGMENTATION
HEAVY ION REACTIONS
INTERACTIONS
LINEAR MOMENTUM
NUCLEAR REACTIONS
PARTICLE INTERACTIONS
PHASE TRANSFORMATIONS
PHOTON EMISSION
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK-GLUON INTERACTIONS
RELATIVISTIC RANGE
TRANSVERSE MOMENTUM