RHIC and the QGP at 10: from the “age of discovery” to the “age of exploration”

Abstract

This year marks the 10th anniversary of the beginning of RHIC operations. Soon after collisions began it was shown that the temperatures and densities reached in Au+Au collisions of 200 GeV per nucleon are vastly above those where hadrons can exist. A new state‐of‐matter is created—the quark‐gluon plasma (QGP). We now know the QGP is strongly interacting and essentially opaque to gluons and quarks passing through it and that it flows like an almost perfect fluid. There is, however, much still to be learned about the QGP’s properties and how the transition from quarks and gluons to hadrons occurs. These issues are the focus of the ongoing research at RHIC and the LHC, where first Pb‐Pb collisions are expected at the end of this year. A new project at RHIC is the beam energy scan. The goal of this endeavor is a more detailed study of the phase diagram of nuclear matter, with the exciting prospect of locating predicted key features such as the critical point—where the phase boundary between the hadronic gas and the QGP ends.