Nuclear Particle Astrophysics (NPA) Seminar, Jacquelyn Noronha-Hostler, Columbia University, “The unreasonable effectiveness of hydrodynamics in heavy ion collisions”

Thursday Sep 10, 2015, 3:30 PM → 4:30 PM US/Eastern

WLC 108

Ultrarelativistic heavy ion experiments have produced the Quark-Gluon Plasma, a novel state of matter where quarks and gluons are the relevant degrees of freedom, which is the hottest, smallest, and most perfect fluid ever made. Studying the Quark Gluon Plasma requires an understanding of quantum chromodynamic phenomena that occur in three different scales: a “macroscopic” scale that is of the order of the radius of a large nucleus ~10 fm, a mesoscale that is on the order of the size of a proton ~1fm, and a microscopic scale that is much smaller, <0.1 fm, than the size of the proton. Surprisingly enough, the Quark Gluon Plasma produced in heavy-ion can be well described by relativistic fluid dynamics with nearly perfect fluidity i.e. where dissipation effects are incredibly small. However, fluid dynamics is an effective theory that is only applicable when there is a large separation between the microscopic and macroscopic scales and, thus, as smaller and smaller collision systems (such as elementary proton-proton collisions) are investigated using fluid dynamics one unavoidably pushes the boundaries of what is understood as a fluid. In this talk I will discuss the scale dependence of known experimental observables and propose a new observable that gives insight into the nature of deconfinement by pinning down the relevant subnucleonic scale in heavy ion collisions.

Noronha-Hostler_NPA_Seminar_09102015.pdf