Departmental Colloquium: Dr. Wei Li
“Quark-Gluon Plasma at the LHC: the hottest matter in the universe”
Quarks and Gluons are the most fundamental building blocks that form the nuclear matter via the strong force. Quantum Chromodynamics (QCD) predicts that when the temperature exceeds about two trillion kelvin, a new state of matter will emerge, in which quarks and gluons become locally deconfined and quasi-free. This so-called "Quark-Gluon Plasma" (QGP) matter is believed to have existed in the early universe in the first few microseconds after the Big Bang. In the past decade, experiments at the Relativistic Heavy Ion Collider (RHIC) made major breakthroughs in identifying a hot and opaque QCD matter that exhibits a nearly perfect fluid nature with close to minimal shear viscosity-to-entropy ratio.
The onset of the Large Hadron Collider (LHC) has opened the door to a variety of new opportunities in the field of high-energy nuclear physics. In this talk, I will review the most striking observations in colliding the ultrarelativistic heavy nuclei, with a focus on the exciting new results from the first heavy-ion data taken at the LHC. Emphasis will be given to the measurements of collective flow and in-medium parton energy loss phenomena, which provide us essential insight in understanding the fluid nature of the QCD matter under extreme condition. Outlook of future programs at the RHIC and LHC will also be discussed.