P. Danielewicz

Determination of the equation of state of dense matter

Nuclear collisions can compress nuclear matter to densities achieved within neutron stars and within core-collapse supernovae. These dense states of matter exist momentarily before expanding. We analyzed the flow of matter to extract pressures in excess of 1034 pascals, the highest recorded under laboratory-controlled conditions. Using these analyses, we rule out strongly repulsive nuclear equations of state from relativistic mean field theory and weakly repulsive equations of state with phase transitions at densities less than three times that of stable nuclei, but not equations of state softened at higher densities because of a transformation to quark matter.

Quantum theory of nonequilibrium processes, I

Greens function techniques for studying nonequilibrium quantum processes are discussed. Perturbation expansions and Greens function equations of motion are developed for noncorrelated and correlated initial states of a system. A transition, from the Kadanoff-Baym Greens function equations of motion to the Boltzmann equation, and specifications of the respective limit, are examined in detail.

Transverse Momentum Analysis of Collective Motion in Relativistic Nuclear Collisions

Abstract A novel transverse-momentum technique is used to analyse charged-particle exclusive data for collective motion in the Ar+KCl reaction at 1.8 GeV/nucleon. Previous analysis of this reaction, employing the standard sphericity tensor, revealed no significant effect. In the present analysis, collective effects are observed, and they are substantially stronger than in the Cugnon cascade model, but weaker than in the hydrodynamical model.

Constraints on the symmetry energy and neutron skins from experiments and theory

The symmetry energy contribution to the nuclear equation of state impacts various phenomena in nuclear astrophysics, nuclear structure, and nuclear reactions. Its determination is a key objective of contemporary nuclear physics, with consequences for the understanding of dense matter within neutron stars. We examine the results of laboratory experiments that have provided initial constraints on the nuclear symmetry energy and on its density dependence at and somewhat below normal nuclear matter density. Even though some of these constraints have been derived from properties of nuclei while others have been derived from the nuclear response to electroweak and hadronic probes, within experimental uncertainties-they are consistent with each other. We also examine the most frequently used theoretical models that predict the symmetry energy and its slope parameter. By comparing existing constraints on the symmetry pressure to theories, we demonstrate how contributions of three-body forces, which are essential ingredients in neutron matter models, can be determined.

Has the QCD critical point been signaled by observations at the BNL relativistic heavy ion collider

The shear viscosity to entropy ratio (

Production of deuterons and pions in a transport model of energetic heavy-ion reactions

\eta/s

Determination of the mean-field momentum-dependence using elliptic flow

) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC (

QUANTUM THEORY OF NONEQUILIBRIUM PROCESSES. II. APPLICATION TO NUCLEAR COLLISIONS

\sqrt{s_{NN}}=200

Elliptic flow: Transition from out-of-plane to in-plane emission in Au + Au collisions

GeV). A very low value is found

Disappearance of elliptic flow: A new probe for the nuclear equation of state

\eta/s \sim 0.1