Closing in on “Perfection”

In a recent preprint

Song, Bass, Heinz, Hirano, and Shen present systematic comparisons of RHIC data on elliptic flow in Au+Au collisions with a hybrid model of the reaction dynamics. They conclude that the kinematic shear viscosity ν = 4πη/s in the quark-gluon plasma phase of the reaction does not exceed 2.5 on average, compared with the lower KSS bound of 1. (more…)

Quark Matter 2009 Highlights

The 21st International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, colloquially referred to as Quark Matter 2009, took place in Knoxville, Tennessee from March 30th to April 4th, 2009. (more…)


Over the past few months a new initiative, called Theory-Experiment Collaboration for Hot QCD Matter (TECHQM), has taken shape, which potentially will have great impact on how our community arrives at scientific conclusions on the nature and properties of hot and dense QCD matter created at the RHIC and LHC facilities. (more…)

Parton cascades and elliptic flow

Three new preprints address the question of what it takes to describe the measured elliptic flow in Au+Au collisions at RHIC in the framework of a partonic Boltzmann equation: (more…)

The String Theory Connection of RHIC

The idea that superstring theory may help inform the physics of relativistic heavy ion collisions begins with Maldacena’s remarkable discovery in 1997 that the (N = 4) supersymmetric Yang-Mills theory in (3+1)-dimensional space-time and 10-dimensional superstring theory in a geometrical background composed of the product of 5-dimensional Anti-deSitter space (AdS) and a 5-dimensional sphere describe the same physics. (more…)

Microscopic Transport Model Primer

Microscopic transport models aim at describing the time-evolution of a heavy-ion collision, either in part or from beginning to end, using microscopic degrees of freedom, i.e. nucleons, hadrons or quarks and gluons. They are based on the solution of a transport equation, which can be derived within the framework of kinetic theory. (more…)

Time-Scales and Flavor Dependence of (Elliptic) Flow

Elliptic flow at ultra-relativistic energies, the preferential emission of matter along the impact parameter axis of the overlap zone of the two colliding nuclei, was first mentioned in our Hydro Primer. The main relevance of elliptic flow lies in the short timescales over which it is generated and its resulting sensitivity to the equation of state of the (QGP) medium. (more…)

Recent Hydro Developments

Improving the application of Relativistic Fluid Dynamics to relativistic heavy-ion collisions is an ongoing challenge and currently a very active area of research: recent notable preprints on the topic are centered around two main themes: (more…)

Consistent Relativistic Hydrodynamics

Stable first-order particle-frame relativistic hydrodynamics for dissipative systems

The authors of this manuscript propose a new formulation of stable first-order relativistic dissipative hydrodynamics in the particle frame, also called the Eckart frame. (more…)

Jet-Broadening in Turbulent Plasmas

This paper presents the first selfconsistent calculation of the broadening of a jet in turbulent color fields. (more…)