Future Physics Capabilities of RHIC

Abstract

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory is a versatile facility for both heavy-ion and polarized-proton collision physics. The initial heavy-ion runs (Au+Au, Cu+Cu, and d+Au) have led to the unexpected discoveries at RHIC that (1) the new state of matter produced is a "nearly-perfect" fluid, (2) fast quarks (jets) lose large amounts of energy, when traversing the medium, (3) the quarks themselves are observed to flow, and (4) forward particle production is lower than expected. The polarized proton (p+p) program has discovered that gluons do not make a maximal contribution to the spin of the proton. Substantial upgrades to the accelerator and experimental detectors are ushering in an exciting transition from discovery to understanding. RHIC is poised to address these fundamental questions of broad significance: (a) What are the phases of QCD matter? (b) What is the wave function of the proton? (c) What is the wave function of a heavy nucleus? (d) What is the nature of non-equilibrium processes in a fundamental theory? After a brief introduction this talk and paper give an abbreviated overview of what has been learned so far, the plan for the mid-term (2006-2011), and the long-range plan (2012 and beyond).