Investigating the strong nuclear interactions under extreme conditions

Abstract

By colliding the nuclei of heavy atoms that have been accelerated to incredible energy, we are able to create exotic states of matter and probe fundamental properties of the universe. In particular, it is believed that extremely high temperatures can be achieved in these relativistic heavy-ion collisions. Under these conditions, the physics is governed by Quantum Chromodynamics (QCD), the fundamental theory of the strong nuclear interactions. According to QCD, at such high temperature there should exist a new phase of matter called the Quark-Gluon Plasma (QGP). Results from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) have already given a qualitative demonstration of the creation of a strongly interacting, almost- perfect fluid QGP. New data from RHIC and LHC will provide an opportunity to quantify properties of the QGP medium, as well as to characterize the non-equilibrium dynamics of the early stages of a collision. I propose here to use state-of-the-art phenomenological and theoretical tools to extract precise quantitative information from these new experimental data. Specifically, it is proposed to obtain the first precise determination of the thermodynamic and transport properties of the QGPshear and bulk viscosity and the equilibrium phase diagram (e.g., the existence and location of a possible critical point)-including a quantitative determination of systematic uncertainty. Simultaneously, it is proposed to study the non-equilibrium, pre-QGP initial stages of these col- lisions, in order to determine the correct description of the low-x regime of the nuclear wavefunction and the dynamic mechanisms that drive the collision system toward equilibrium. (AU)