Soft electromagnetic radiations from relativistic heavy ion collisions

Journal Article · Sat Mar 01 04:00:00 EST 1997 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.55.1467· OSTI ID:515651

Pal, D; Roy, P K; Sarkar, S; Srivastava, D K ^[1]; Sinha, B ^[1]

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1. Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Calcutta 700 064 (India)

The production of low-mass dileptons and soft photons from thermalized quark-gluon plasma (QGP) and hadronic matter in relativistic heavy ion collisions is evaluated. A boost invariant longitudinal and cylindrically symmetric transverse expansion of the systems created in central collision of lead nuclei at CERN SPS, BNL RHIC, and CERN LHC, and undergoing a first-order phase transition to hadronic matter is considered. A large production of low-mass (M{lt} 0.3 GeV) dileptons, and soft photons (p{sub T}{lt}0.4 GeV) is seen to emanate from the bremsstrahlung of quarks and pions. We find an increase by a factor of 2 to 4 in the low-mass dilepton and soft-photon yield as we move from SPS to RHIC energies, and an increase by an order of magnitude as we move from SPS to LHC energies. Most of the soft radiations are found to originate from pion driven processes at SPS and RHIC energies, while at the LHC energies the quark and the pion driven processes contribute by a similar amount. The study of the transverse mass distribution is seen to provide interesting details of the evolution. We also find a unique universal behavior for the ratio of M{sup 2} weighted transverse mass distribution for M= 0.1 GeV to that for M= 0.2 and 0.3 GeV, as a function of M{sub T}, for SPS, RHIC, and LHC energies, in the absence of transverse expansion of the system. A deviation from this universal behavior is seen as a clear indication of the flow. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 515651
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 3 Vol. 55; ISSN PRVCAN; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
HEAVY ION REACTIONS
LEPTONS
MASS
PARTICLE PRODUCTION
PHASE TRANSFORMATIONS
PHOTONS
PIONS
QUARK MATTER
RELATIVISTIC RANGE