From SPS to RHIC: Breaking the Barrier to the Quark-Gluon Plasma

After 15 years of heavy-ion collision experiments at the AGS and SPS, the recent turn-on of RHIC has initiated a new stage of quark-gluon plasma studies. I review the evidence for deconfined quark-gluon matter at SPS energies and the recent confirmation of some of the key ideas by the new RHIC data. Measurements of the elliptic flow at RHIC provide strong evidence for efficient thermalization during the very early partonic collision stage, resulting in a well-developed quark-gluon plasma with almost ideal fluid-dynamical collective behaviour and a lifetime of several fm/c.Comment: LaTex 12 pages, including 6 figures. Opening talk at the Conference "QCD@work", Martinafranca (Bari), June 16-20, 200

Thermalization at RHIC

Ideal hydroynamics provides an excellent description of all aspects of the single-particle spectra of all hadrons with transverse momenta below about 1.5-2 GeV/c at RHIC. This is shown to require rapid local thermalization at a time scale below 1 fm/c and at energy densities which exceed the critical value for color deconfinement by an order of magnitude. The only known thermalized state at such energy densities is the quark-gluon plasma (QGP). The rapid thermalization indicates that the QGP is a strongly interacting liquid rather than the weakly interacting gas of quarks and gluons that was previously expected.Comment: Erroneous formulation on p.2 corrected. 16 pages, incl. 4 postscript figures. Invited talk presented at HADRON-RANP 2004 (IX Hadron Physics and VII Relativistics Aspects of Nuclear Physics: A Joint Meeting on QCD and QGP), Angra dos Reis, Rio de Janeiro, Brazil, March 28 - April 3, 2004. To appear in AIP Conference Proceedings (M. Bracco, M. Chiapparini, et al., eds.

Event-by-event hydrodynamics for heavy-ion collisions

We compare v2/{\epsilon}2 and v3/{\epsilon}3 from single-shot and event-by-event (2+1)-dimensional hydrodynamic calculations and discuss the validity of using single-shot calculations as substitutes for event-by-event calculations. Further we present a proof- of-concept calculation demonstrating that v2 and v3 together can be used to strongly reduce initial condition ambiguities.Comment: 3 pages, 2 figures. Contribution to the proceedings for 19th Particles & Nuclei International Conference (PANIC11

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