Heavy Ion Collisions

Lattice QCD predicts a phase transition between hadronic matter and a system of deconfined quarks and gluons (the Quark Gluon Plasma) at high energy densities. Recent results from the Brookhaven Relativistic Heavy Ion Collider (RHIC) dedicated to the study of QCD at extreme densities will be discussed and compared to measurements obtained at the CERN Super Proton Synchrotron (SPS).Comment: Invited talk at the XXIII Physics in Collisions Conference (PIC03), Zeuthen, Germany, June 2003, 14 pages, LaTeX, 13 eps figures. PSN SAAT0

Single particle inclusive spectra, HBT and elliptic flow; a consistent picture at RHIC?

In these proceedings we will present the preliminary identified single particle inclusive spectra, the identified particle elliptic flow and the HBT versus the reaction plane measured with the STAR detector at RHIC. So far none of the theoretical space-time models has been able to describe the combination of these measurements consistently. In order to see if our measurements can be understood in the context of a simple hydro-motivated blast wave model we extract the relevant parameters for this model, and show that it leads to a consistent description of these observables.Comment: 9 pages, 5 figures (in eps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL http://ismd31.ccnu.edu.cn

Collective Expansion at the LHC: selected ALICE anisotropic flow measurements

The collective expansion of matter created in collisions of heavy-ions, ranging from collision energies of tens of MeV to a few TeV per nucleon pair, proved to be one of the best probes to study the detailed properties of these unknown states of matter. Collective expansion originates from the initial pressure gradients in the created hot and dense matter. These pressure gradients transform the initial spatial deformations and inhomogeneities of the created matter into momentum anisotropies of the final state particle production, which we call anisotropic flow. These momentum anisotropies are experimentally characterised by so-called flow harmonics. In this paper I review ALICE measurements of the flow harmonics at the CERN Large Hadron Collider and discuss some of the open questions.Comment: 25 pages, 15 figures, invited review for J. Phys. G Focus Issue on "Collective flow and transport phenomena in heavy ion physics" Edited by Takeshi Kodama, Nu Xu and Horst Stoecke

How much does the hadronic phase contribute to the observed anisotropic flow at the LHC?

Elliptic flow signals the presence of multiple interactions between the constituents of the created matter in heavy-ion collisions. This includes possible contributions from the different phases, including the hadronic phase. In these proceedings I will first show that the energy dependence of elliptic flow, based on recent ALICE and STAR beam energy scan measurements, can largely be understood in terms of a boosted thermal system. In addition, a detailed comparison between the identified particle elliptic flow measured by the ALICE collaboration and viscous hydrodynamical model calculations with and without a hadronic afterburner is performed to constrain the possible effects of individual hadron-hadron re-interaction cross-sections.Comment: 10 pages, 8 figures, proceedings Resonance Workshop at Catania, version two updated with referee comment

Elliptic flow measurements from STAR

In these proceedings some of the highlights of the elliptic flow measurements from STAR at $\sqrt{s_{_{NN}}} =$ 130 and 200 GeV for Au+Au collisions are presented.Comment: Proceedings for the 19th Winter Workshop on Nuclear Dynamics, Breckenridge, Colorado, March 8-15, 2003, 6 pages, 8 figure

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Collective flow and viscosity in relativistic heavy-ion collisions

Collective flow, its anisotropies and its event-to-event fluctuations in relativistic heavy-ion collisions, and the extraction of the specific shear viscosity of quark-gluon plasma (QGP) from collective flow data collected in heavy-ion collision experiments at RHIC and LHC are reviewed. Specific emphasis is placed on the similarities between the Big Bang of our universe and the Little Bangs created in heavy-ion collisions.Comment: 38 pages (incl. 11 figures), 145 references. Invited review prepared for Annual Review in Nuclear and Particle Physics 63 (2013

Collective phenomena in non-central nuclear collisions

Recent developments in the field of anisotropic flow in nuclear collision are reviewed. The results from the top AGS energy to the top RHIC energy are discussed with emphasis on techniques, interpretation, and uncertainties in the measurements.Comment: Review paper, 56 pages, as accepted for publicatio