TY  - INPR
A1  - Reiter, Manuel
A1  - Dumitru, Adrian Bogdan
A1  - Brachmann, Jörg
A1  - Maruhn, Joachim
A1  - Stöcker, Horst
A1  - Greiner, Walter
T1  - Entropy production in collisions of relativistic heavy ions : a signal for quark-gluon plasma phase transition?
N2  - Entropy production in the compression stage of heavy ion collisions is discussed within three distinct macroscopic models (i.e. generalized RHTA, geometrical overlap model and three-fluid hydrodynamics). We find that within these models \sim 80% or more of the experimentally observed final-state entropy is created in the early stage. It is thus likely followed by a nearly isentropic expansion. We employ an equation of state with a first-order phase transition. For low net baryon density, the entropy density exhibits a jump at the phase boundary. However, the excitation function of the specific entropy per net baryon, S/A, does not reflect this jump. This is due to the fact that for final states (of the compression) in the mixed phase, the baryon density \rho_B increases with \sqrt{s}, but not the temperature T. Calculations within the three-fluid model show that a large fraction of the entropy is produced by nuclear shockwaves in the projectile and target. With increasing beam energy, this fraction of S/A decreases. At \sqrt{s}=20 AGeV it is on the order of the entropy of the newly produced particles around midrapidity. Hadron ratios are calculated for the entropy values produced initially at beam energies from 2 to 200 AGeV.
Y1  - 1998
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3374
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30-20371
ER  -