The THURIC network will concentrate on the following three topics:

  • The properties of the plasma before hadronisation and how the phase transition toward the hadronic world takes place.
  • The modification of hard probes due to the quark gluon plasma through which they pass and the information the hard probes carry about this interaction.
  • A detailed study of the initial thermalisation.

Description of work and role of partners
As mentioned in the Objectives, there are three fields where the network foresees to invest its resources:

Plasma and phase transition
The simulation programs which yield to a large extent similar results for the single particle observables for light mesons and baryons use quite different initial conditions and descriptions of the expansion. This is a consequence of the fact that the distribution of these particles is that one expects from a source in statistical equilibrium at the critical temperature and so almost all information about the plasma during the expansion is erased.
Some of the simulation programs are based on ideal hydrodynamics but use fluctuation initial conditions event by event hydrodynamics), some of them on viscous hydrodynamics with event averaged initial conditions, ome of them are cascade type calculations.
In the last year it has been realized that there are observables which give additional information on the properties of the plasma during the expansion. They include multiparticle correlations (ridge, Hanbury Brown nd Twiss (HBT) effect) formed due to causality reasons at the beginning of the expansion, the emission of dileptons and photons as well as the observables of heavy mesons which do not come to equilibrium with the xpanding medium.
It will be the task of the groups of Bergen, Budapest, Frankfurt, Giessen, Saclay, Lyon and Nantes to develop their approach to make a detailed comparison with multiparticle correlations and heavy quark data possible and then to confront their approach with data. The group of Florence will study the possible influence of spin degrees of freedom on the hydrodynamical expansion of the plasma and their role in the dissipation. The roups of Wuppertal, Lyon and Darmstadt will make improvements on the urgently needed hadron properties close to the critical point in infinite matter, a pre-requisite for the study of expanding matter.

Hard probes
The present data of heavy meson can be described with pQCD. But these calculations suffer from many little known quantities. They include the initial distribution of heavy quarks and of fast light quarks, depending of he little known structure functions, the unknown cross section of J/psi mesons with the plasma environment and he influence of the Landau Pomerantschuk Migdal (LPM) effect in a strongly absorptive medium.
It will be the tasks of the groups in Frankfurt, Helsinki, Catania, Giessen and Nantes to study the LPM effect as well as the production of these particles and their interaction. The expected LHC and new RHIC data, where a new identification of heavy mesons is foreseen, will allow for checking the prediction of this theoretical development against experimental data.

Initial state
The fast equilibration in a time scale of 1fm/c, needed if the initial condition for hydrodynamical calculations is correct, is still a mystery but recently it has turned out in an exploratory study that many body processes and gluon emission accelerate the thermalization tremendously.

It will be the task of the groups in Barcelona, Frankfurt and Giessen to develop their programs to a point that predictions become realistic and that it can be verified whether instabilities and many body collisions give different predictions for observables.

The HadronPhysics3 project is supported by the European Union
under the 7th Framework Capacities Programme in the area of Research Infrastructures (RI).