Brian Cole
Columbia University

Ulrich Heinz
Ohio State University

Peter Jacobs
Lawrence Berkeley Laboratory

Yuri Kovchegov
The Ohio State University

Berndt Mueller
Duke University

Jamie Nagle
University of Colorado

Program Coordinator:
Inge Dolan
(206) 685-4286

Questions Emerging from Discussions at the INT Program Quantifying the Properties of Hot QCD Matter

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Quantifying the Properties of Hot QCD Matter

May 24 - July 16, 2010

The program will focus on quantitative study of hot QCD matter, emphasizing rigorous comparison of theoretical models and experimental data. The goal is to reach validated, quantitative conclusions about properties of hot QCD matter such as the equation of state, shear and bulk viscosities, and parton stopping power. The program brings together experimentalists working at RHIC and LHC with theorists working on high temperature QCD, heavy ion collision dynamics, low-x physics, and strongly coupled systems.

The study of QCD matter at high temperature is of fundamental and broad interest. Bulk QCD matter and its possible phase transitions can be explored in the laboratory through the collision of heavy atomic nuclei at ultra-relativistic energies. Such studies have been carried out for three decades, reaching full maturity with the Relativistic Heavy Ion Collider (RHIC) at Brookhaven. The startup of the LHC at CERN will extend the nuclear collision energy frontier, providing new insights into RHIC results and enabling qualitatively new measurements.

The most significant experimental discoveries at RHIC thus far are the large collective flow, apparently created at the partonic level, and the large suppression of high-energy hadrons due to interactions of energetic partons in the hot medium. When combined with theoretical calculations and phenomenological modeling, these measurements indicate that the medium formed in nuclear collisions at RHIC is a strongly coupled, near-inviscid, color-opaque fluid, with initial energy density many times that of normal, cold nuclear matter. These results have had a large impact in other areas of physics, seeding new insights into the structure of hadrons at very high energy, the properties of strongly coupled fluids, and the phenomenology of the gauge/gravity correspondence.

Ultra-relativistic nuclear collisions are by their nature highly dynamic. The connection between experimental observables and theoretical calculations of equilibrium properties of QCD matter requires accurate and reliable dynamical modeling of the various stages of a heavy ion collision. Similarly detailed and accurate modeling is required for dynamical probes of hot QCD matter, such as the energy loss of gluon and light quark jets, and of heavy quarks.

At present, the conclusion that the medium generated at RHIC is a strongly coupled, near-inviscid, color-opaque fluid, with large initial energy density, should be considered to be qualitative, based on dynamical models with in some cases poorly constrained assumptions or approximations. There is a wide consensus that the field must now aim to achieve quantitative understanding of hot QCD matter, going beyond the current qualitative insights. Recent years have seen the accumulation of a wealth of data and significant advances in theory, which together will enable quantitative assessment and systematic improvement in the accuracy of modeling of relativistic heavy ion collisions. This program brings together theorists and experimentalists with expertise in various aspects of this problem, at an opportune moment to evaluate the progress and to exploit it for a deeper understanding of the properties and behavior of hot QCD matter.

The preliminary outline of the eight-week program is as follows:

The order of topics may be rescheduled due to availability of key participants.

The dates of the program overlap with those of the International Nuclear Physics Conference 2010 (INPC2010), which will be held in Vancouver, Canada, July 4-9 2010. The conference website is