Lectures on the Theory of High Energy A+A at RHIC

In these lectures aspects of current theory used to interpret the preliminary data on ultra-relativistic nuclear collisions at RHIC energies in terms of the physical properties of QCD matter at extreme densities are introduced. Topics include: What are the physics questions at SPS and RHIC?, Geometrical vs Dynamical features of A+A, The interplay of computable Hard pQCD vs phenomenological Soft dynamics, Baryon number transport and Junctions, How can we compute and get experimental control over the initial conditions?, How to reconcile apparent hydrodynamic behavior with partonic/hadronic transport theory. I use the Preliminary RHIC data available up to June 1,2001 to illustrate these topics. Since the main new observable at RHIC relative to SPS is jet quenching, I elaborate on this ``tomographic’’ probe of ultra-dense matter. The possible discovery of jet quenching at RHIC by STAR and PHENIX is highlighted.