arXiv subjects

Georg Wolschin

Publications and source records attributed to Georg Wolschin.

41 records · Page 3Linked to original sources

arXiv2006

Time evolution of relativistic d + Au and Au + Au collisions

The evolution of charged-particle production in collisions of heavy ions at relativistic energies is investigated as function of centrality in a nonequilibrium-statistical framework. Precise agreement with recent d + Au and Au + Au data at sqrt(s_NN) = 200 GeV is found in a Relativistic Diffusion Model with three sources for particle production. Only the midrapidity source comes very close to local equilibrium, whereas the analyses of the overall pseudorapidity distributions show that the systems remain far from statistical equilibrium.

hep-ph↗

arXiv2005

Local Thermalization in the d + Au System

The extent of a locally equilibrated parton plasma in d + Au collisions at sqrt(s_NN) = 200 GeV is investigated as a function of collision centrality in a nonequilibrium-statistical framework. Based on a three-sources model, analytical solutions of a relativistic diffusion equation are in precise agreement with recent data for charged-particle pseudorapidity distributions. The moving midrapidity source indicates the size of the local thermal equilibrium region after hadronization. In central d + Au collisions it contains about 19% of the produced particles, and its relative importance rises with decreasing centrality.

hep-ph↗

arXiv2005

Rapidity equilibration and longitudinal expansion at RHIC

The evolution of net-proton rapidity spectra with sqrt(s_NN) in heavy relativistic systems is proposed as an indicator for local equilibration and longitudinal expansion. In a Relativistic Diffusion Model, bell-shaped distributions in central collisions at AGS energies and double-humped nonequilibrium spectra at SPS show pronounced longitudinal collective expansion when compared to the available data. The broad midrapidity valley recently discovered at RHIC in central Au+Au collisions at sqrt(s_NN) = 200 GeV indicates rapid local equilibration which is most likely due to deconfinement, and fast longitudinal expansion of the locally equilibrated subsystem. A prediction is made for Au+Au at sqrt(s_NN)= 62.4 GeV.

hep-ph↗

arXiv2003

Diffusion and local deconfinement in relativistic systems

In relativistic systems at RHIC energies, new deconfinement signatures emerge and indicate an increasingly clear separation between soft hadronic processes, and hard partonic interactions in a locally deconfined subsystem. Here the emphasis is on longitudinal variables, namely, net-baryon rapidity distributions. As described in a Relativistic Diffusion Model, they change from bell-shaped at the lower to double-humped at the higher SPS-energy, but do not reach local statistical equilibrium. At sqrt(sNN) = 200 GeV in the Au-Au system, however, they are shown to consist of three components. In addition to the nonequilibrium contributions, a third fraction close to midrapidity containing Z_eq = 22 protons reaches local statistical equilibrium in a discontinuous transition. It may be associated with a deconfinement of the participant partons and thus, serve as a signature for Quark-Gluon Matter formation.

hep-ph↗

arXiv2003

Anomalous net-baryon-rapidity spectra at RHIC

Net-baryon rapidity distributions in central Au+Au collisions at 200 GeV per nucleon are shown to consist of three components. The nonequilibrium contributions are accounted for in a Relativistic Diffusion Model. Near midrapidity, a third fraction containing approximately 22 protons reaches local statistical equilibrium in a discontinuous transition. It may be associated with a deconfinement of the participant partons and thus, serve as a signature for Quark-Gluon Matter formation.

hep-ph↗