Entropy Production in Collisions of Relativistic Heavy Ions -- a signal for Quark-Gluon Plasma phase transition?

Abstract

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 ρ_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.

17 pages, 8 figures, uses epsfig.sty; Submitted to Nucl.Phys. A

References in corpus (6)

• Excluded volume hadron gas model for particle number ratios in A+A collisions
• Equation of State, Radial Flow and Freeze-out in High Energy Heavy Ion Collisions
• Evidence for a high entropy phase in nuclear collisions
• Chemical equilibration of strangeness
• Hadron and hadron-cluster production in a hydrodynamical model including particle evaporation
• Probes for the early reaction dynamics of heavy-ion collisions at AGS and SPS

Cited by in corpus (18)

• Relativistic Heavy-Ion Collisions within 3-Fluid Hydrodynamics: Hadronic Scenario
• (3+1)-Dimensional Hydrodynamic Expansion with a Critical Point from Realistic Initial Conditions
• Exploring the partonic phase at finite chemical potential within an extended off-shell transport approach
• Anisotropic hydrodynamic modeling of 2.76 TeV Pb-Pb collisions
• Alternative Scenarios of Relativistic Heavy-Ion Collisions: I. Baryon Stopping
• Direct Emission of multiple strange baryons in ultrarelativistic heavy-ion collisions from the phase boundary
• Dynamical Freeze-out in 3-Fluid Hydrodynamics
• Holographic Entanglement Entropy in Anisotropic Background with Confinement-Deconfinement Phase Transition
• Alternative Scenarios of Relativistic Heavy-Ion Collisions: II. Particle Production
• Collective Flow in Heavy-Ion Collisions from AGS to SPS
• Alternative Scenarios of Relativistic Heavy-Ion Collisions: III. Transverse Momentum Spectra
• Elliptic Flow in Heavy-Ion Collisions at Energies $\sqrt{s_{NN}}=$ 2.7--39 GeV
• The directed flow maximum near c_s=0
• Entropy production and reheating at the chiral phase transition
• Entropy Production and Effective Viscosity in Heavy-Ion Collisions
• Distinguishing Hadronic Cascades from Hydrodynamic Models in Pb(160 AGeV)+Pb Reactions by Impact Parameter Variation
• Phase Structure in a Hadronic Chiral Model
• Hadronic Entropy Enhancement and Low Density QGP