The Ugly Duckling and the Swan: the Quark-Gluon Plasma and heavy ion collisions

Robert Pisarski, PhD; Department of Physics, Brookhaven National Laboratory

I give a pedagogical and historical overview of the search for the Quark-Gluon plasma (QGP) in the collisions of heavy ions. I begin with a brief review of why we expect a QGP to be formed at high temperature. In this, numerical simulations in lattice Quantum ChromoDynamics (QCD) form the bedrock of the field. In particular, they demonstrate the relationship between deconfinement and the restoration of chiral symmetry. At the SPS at CERN, I discuss the suppression of J/Psi mesons, and the excess of dileptons below the rho meson. Bjorken first noticed that a "plateau" may emerge at high energies, and produce a regime at high temperature, and low chemical potential. At colliders such as RHIC, at Brookhaven, and the LHC, at CERN, I discuss two notable signals: the utility of nearly ideal hydrodynamics, and jet quenching. The new frontier is going down to moderate collision energies, which there is net excess of baryons. Possible phenomena in this region include a critical end point and moat regimes.  

Speaker Bio: Rob Pisarski was an undergraduate at Yale, where he studied under Feza Gursey.  He received his PhD from Princeton in 1979, with David Gross. After returning to Yale as the last Gibbs Fellow, and positions at Santa Barbara and Fermilab, he went to Brookhaven in 1989, where he has been since. Besides his work on Chern-Simons theories in the '80s, he is known for his work on gauge theories at non-zero temperature and density, including Hard Thermal Loops, effective theories of deconfinement, quarkyonic matter, and most recently, moat spectra.