Coherence and incoherence in the photon and dilepton production by bremsstrahlung in relativistic heavy-ion collisions

Journal Article · Tue Dec 10 00:00:00 EST 1991 · International Journal of Modern Physics A; (United States)

DOI:https://doi.org/10.1142/S0217751X9100246X· OSTI ID:5303040

Lippert, T; Thiel, J; Grun, N; Scheid, W ^[1]

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1. Inst. fuer Theoretische Physik der Justus-Liebig-Universitat, Giessen (DE)

Due to the strong collective deceleration during the initial stage of relativistic heavy ion collisions, the nuclear matter irradiates real and virtual bremsstrahlung. This paper describes the process of bremsstrahlung emission in the framework of a semiclassical model in order to study coherence and incoherence effects in the production process. Guided by the intuitive notation of shock fronts being formed between the incident nuclei, we use a simple parametrization of the nuclear current density. The photon spectrum is studied up to photon energies of 300 MeV. In particular, a gradual transition from the coherent production process of low-energy photons to the incoherent one for hard photons is demonstrated. For heavy collision systems coherence effects in the photon spectra dominate, showing characteristic structures arising from shock fronts. The dilepton spectrum is described in first-order perturbation theory. Generally, dileptons are found to be produced incoherently. Only in the case of dielectron production with small invariant pair masses do moderate coherence effects survive.

• OSTI ID: 5303040
• Journal Information: International Journal of Modern Physics A; (United States), Vol. 6:29; ISSN 0217-751X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
HEAVY ION REACTIONS
BREMSSTRAHLUNG
LEPTONS
PRODUCTION
PHOTONS
ACCELERATION
BOUND STATE
COHERENT RADIATION
ELECTRON PAIRS
INVARIANCE PRINCIPLES
MASS SPECTRA
MEV RANGE 100-1000
NUCLEAR MATTER
PERTURBATION THEORY
RELATIVISTIC RANGE
SEMICLASSICAL APPROXIMATION
SHOCK WAVES
BOSONS
CHARGED-PARTICLE REACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
MASSLESS PARTICLES
MATTER
MEV RANGE
NUCLEAR REACTIONS
RADIATIONS
SPECTRA
663450* - Heavy-Ion-Induced Reactions & Scattering- (1992-)
663110 - General & Average Properties of Nuclei & Nuclear Energy Levels- (1992-)
662130 - General Theory of Particles & Fields- S-Matrix Theory
Relativistic Scattering Theory- (1992-)