Flow and Wake in the Quark-Gluon Liquid produced at RHIC
Julia Velkovska Vanderbilt U.
Friday, Dec. 21, at 4p.m. in Wilson Hall, room 1 West.
Abstract: The experimental collaborations based on the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory recently announced the discovery of an extraordinarily dense and hot state of matter which exhibits properties of a near perfect liquid. While it was expected that at RHIC energies the head-on collisions of gold ions will lead to deconfinement of the quarks and gluons inside them, the quark-gluon plasma (QGP) showed surprising collective properties, contrary to the predictions for a gas of free quarks and gluons. The matter "flows", i.e. - responds collectively to variations of pressure across the volume formed by the colliding nuclei. In most recent correlation measurements a backwash of particles has been observed in conjunction with a fast moving particle propagating through the QGP. What excitations produce the wakes observed in the experiment? Is it a sound wave, Cherenkov radiation of gluons or some other excitation moving through the QGP? This talk will review the experimentally observed collective phenomena and the emerging theoretical interpretations.