Horst Stoecker

Excluded volume effect for the nuclear matter equation of state

We present the thermodynamically consistent procedure to introduce the excluded volume effect into the equation of state of nuclear matter. Implications are discussed in the framework of a mean-field model for hadrons with eigenvolume.

Dependence of particle production in high-energy heavy ion collisions on the nuclear equation of state

The total pion production cross section in central high energy heavy ion collisions depends strongly on the nuclear equation of state. This fact can be used to detect phase transitions from normal nuclear matter into abnormal superdense states (density isomers).

Quasistable black holes at the Large Hadron Collider

We adress the production of black holes at LHC and their time evolution in space times with compactified space like extra dimensions. It is shown that black holes with life times of hundred fm/c can be produced at LHC. The possibility of quasi-stable remnants is discussed.

Equation of State, Spectra and Composition of Hot and Dense Infinite Hadronic Matter in a Microscopic Transport Model ∗

Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine(February 9, 2008)Equilibrium properties of infinite relativistic hadron matter are investi-gated using the Ultrarelativistic Quantum Molecular Dynamics (UrQMD)model. The simulations are performed in a box with periodic boundary con-ditions. Equilibration times depend critically on energy and baryon densities.Energy spectra of various hadronic species are shown to be isotropic andconsistent with a single temperature in equilibrium. The variation of energydensity versus temperature shows a Hagedorn-like behavior with a limitingtemperature of 130±10 MeV. Comparison of abundances of different particlespecies to ideal hadron gas model predictions show good agreement only ifdetailed balance is implemented for all channels. At low energy densities,high mass resonances are not relevant; however, their importance raises withincreasing energy density. The relevance of these different conceptual frame-works for any interpretation of experimental data is questioned.

van der Waals Interactions in Hadron Resonance Gas: From Nuclear Matter to Lattice QCD

An extension of the ideal hadron resonance gas (HRG) model is constructed which includes the attractive and repulsive van der Waals (VDW) interactions between baryons. This VDW-HRG model yields the nuclear liquid-gas transition at low temperatures and high baryon densities. The VDW parameters a and b are fixed by the ground state properties of nuclear matter, and the temperature dependence of various thermodynamic observables at zero chemical potential are calculated within the VDW-HRG model. Compared to the ideal HRG model, the inclusion of VDW interactions between baryons leads to a qualitatively different behavior of second and higher moments of fluctuations of conserved charges, in particular in the so-called crossover region T∼140-190  MeV. For many observables this behavior resembles closely the results obtained from lattice QCD simulations. This hadronic model also predicts nontrivial behavior of net-baryon fluctuations in the region of phase diagram probed by heavy-ion collision experiments. These results imply that VDW interactions play a crucial role in the thermodynamics of hadron gas. Thus, the commonly performed comparisons of the ideal HRG model with the lattice and heavy-ion data may lead to misconceptions and misleading conclusions.

Local equilibrium in heavy ion collisions: Microscopic model versus statistical model analysis

The assumption of local equilibrium in relativistic heavy ion collisions at energies from 10.7 AGeV (AGS) up to 160 AGeV (SPS) is checked in the microscopic transport model. Dynamical calculations performed for a central cell in the reaction are compared to the predictions of the thermal statistical model. We find that kinetic, thermal and chemical equilibration of the expanding hadronic matter are nearly approached late in central collisions at AGS energy for

Hadronic freeze-out following a first order hadronization phase transition in ultrarelativistic heavy-ion collisions

t \geq 10

Hydrodynamics near a chiral critical point

fm/

Nonequilibrium initial conditions from perturbative QCD for relativistic and ultrarelativistic heavy ion collisions

c

{ital J}/{ital {Psi}} Production, {ital {chi}} Polarization, and Color Fluctuations

in a central cell. At these times the equation of state may be approximated by a simple dependence