Description
Quantum Chromodynamics has long predicted a transition from normal hadronic matter to a phase where the quarks and gluons are no longer bound together and can move freely. There has been a wordwide hunt over several decades for this new phase, called quark gluon plasma. It is now produced regularly in collisions of heavy nuclei at very high energy at both the Relativistic Heavy Ion Collider (RHIC) in the U.S. and at the LHC in Europe.
The quark gluon plasma is very surprising, as it is a strongly coupled liquid rather than a gas as everyone expected. Its vanishingly small shear viscosity to entropy density ratio means that it flows essentially without internal friction, making it one of the most 'perfect' liquids known. The strong coupling requires novel theoretical methods to understand the dynamics of this liquid. Interactions with the liquid cause transiting fast quarks and gluons to deposit a large amount of energy, though the exact mechanism is not yet fully understood. I will describe the discovery and properties of this novel matter, and discuss how we probe it by measuring jets of particles arising from fast quarks and gluons.
The quark gluon plasma is very surprising, as it is a strongly coupled liquid rather than a gas as everyone expected. Its vanishingly small shear viscosity to entropy density ratio means that it flows essentially without internal friction, making it one of the most 'perfect' liquids known. The strong coupling requires novel theoretical methods to understand the dynamics of this liquid. Interactions with the liquid cause transiting fast quarks and gluons to deposit a large amount of energy, though the exact mechanism is not yet fully understood. I will describe the discovery and properties of this novel matter, and discuss how we probe it by measuring jets of particles arising from fast quarks and gluons.