REPORT

The goal of the Workshop was to discuss the present state and future opportunities in several issues relevant to the description of ultrarelativistic heavy ion collisions within the framework of quantum chromodynamics, in particular:

1. Parton structure function of nuclei, especially at small $x$: shadowing of quark and gluon distribution functions, semiclassical methods for large nuclei, and parton-parton correlations in nuclei. The impact of recent results from HERA was discussed in detail.
2. Theoretical foundations of the space-time picture for partonic cascades: coherence and decoherence of parton wavefunctions, propagation of off-shell partons, QCD transport theory and entropy creation.
3. Medium modifications of perturbative QCD cross sections: color screening, collision-induced radiation suppression, color conductivity, parton damping rates and multi-gluon interactions.
4. Signals for the pre-equilibrium and equilibrium quark-gluon plasma, focusing on electromagnetic and heavy flavor probes of the dense QCD matter.

In a mini-workshop format, the invited leading representatives of the experimental programs at HERA and the CERN-SPS, as well as of the RHIC and LHC heavy ion programs, presented an overview of the physics results and future plans.

The level of the discussions was excellent throughout, thanks to the outstanding participants. Participation was by invitation only; almost all invited researchers attended the Workshop. Two Russian scientists who could not participate due to visa difficulties were the exception.

There was unanimous agreement among the participants that the Workshop was extremely stimulating and intense, and many expressed their hope that a follow-up workshop can be held in the future. Progress in the theoretical understanding was made on all important issues. Several interesting new ideas were generated in the discussions during the Workshop and were presented and discussed publicly on the last day. In summary, the Workshop was a success far beyond the initial expectations. We are confident that it will have a major impact on future theoretical research in the field of QCD and relativistic heavy ions.

Finally, we would like to express our warmest gratitude to the Directors and the very helpful staff of the ECT* who greatly contributed to the success of our meeting.