Strongly coupled quark-gluon plasma in heavy ion collisions

The field of relativistic heavy ion collisions spans over five decades ranging from the formulation of scientific goals and early experiments at Berkeley in the 1960s with mostly lighter heavy ions via the start of operation of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven in the year 2000 up to the Large Hadron Collider (LHC) at CERN, where the first experiments took place in 2010. The data from the RHIC and LHC experiments and their theoretical explanations outlined in this review provide convincing evidence for the creation of a strongly coupled quark-gluon plasma, i.e., a nearly perfect fluid with large entropy density to viscosity ratio formed during collision.