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ReteQuarkonii aims at studying the production of quarkonia in hadronic collisions at ultra-relativistic energies. In the next 10 years, the future Large Hadron Collider (LHC) will open new possibilities for studying the properties of the strongly interacting matter at high temperature and the non-perturbative features of QCD. Quarkonia will be abundantly produced and correlations with other global observables of the heavy ion collision like centrality and/or reaction plane will allow a detailed investigation of the quark-gluon plasma (QGP) phases. In such high-energy hadronic collisions, quarkonia will also be abundantly produced in diffractive and electromagnetic processes, including both diffractive pomeron- and photon-induced quarkonium production.

The present proposal of networking aims at :

• coordinating the future measurements on quarkonium production in hadronic collisions at ultra relativistic energies;
• promoting the theoretical activities around this topic of research.

The experiments at LHC will provide crucial information about the production mechanism of J/y in Pb+Pb collisions at 5.5 TeV. In particular, the dependence of the J/y yield with centrality, the amount of J/y   elliptic flow and the J/y polarization will allow to study the properties of the QGP. Moreover the LHC will open the possibility of detecting bottomonium resonances in such collisions. The latter contain b quarks and will be complementary to charmonium (c-quark systems) measurements. Recombination of bottom quarks is expected to be relatively small at LHC energies and dissociation temperatures of bottomonia due to the Debye screening cover a large temperature range allowing to probe the structure of the produced QGP. The proton runs at LHC will allow for studying the production of quarkonia in proton-proton collisions. These measurements will provide a robust baseline to study quarkonium production in Pb+Pb collisions. In addition, this measurement will improve our understanding of production of quarkonia in hadronic collisions. Particularly, the study of J/y yields and polarisation at high transverse momentum will represent a crucial test of the existing theoretical models of quarkonium production. Moreover, the measurement of quarkonium production in proton or deuteron induced collisions will be crucial to understand the mechanisms of quarkonia production in cold nuclear matter at ultra-relativistic energies. Finally, the measurement of open charm and open beauty production will be crucial in order to normalize the quarkonium production yields and to quantify the heavy quark recombination process.

In the meantime, the experiments at RHIC will continue their program. PHENIX already measured an anomalous J/y suppression. In the time of this network, its interpretation will be refined through several new measurements, the most important of which coming from the installation of a silicon vertex detector, likely to happen in 2009. By locating secondary vertices, this new apparatus will allow precise open charm measurements and charm/beauty separation. In themselves interesting, these measurements will serve as a new baseline for the J/y production. Other possible measurements are y', c_c and ¡ production, J/y elliptic flow and J/y polarization, energy density scans through lighter ions or lower energy, etc. The proposed network will allow experimentalists from the LHC and RHIC communities, as well as theorists, to compare the quarkonia behaviour at the two different energy regimes. A strong interplay is expected: the RHIC experience will be beneficial to the LHC physicists, while the new features measured at LHC could shed light on the RHIC results and suggest new data analyses. All these studies on quarkonia physics will have a positive impact in the project of CBM experiment at the FAIR facility in Darmstadt.

The understanding of diffractive quarkonia production at LHC energies necessitates the understanding of electromagnetic processes. Diffractive J/y production, for example, can proceed through Odderon-Pomeron or Photon-Pomeron fusion. The cross section of the photon contribution is predicted to be larger by a factor of ten as compared to the Odderon contribution, hence a careful analysis of the Photon-Pomeron amplitude is necessary. The diffractive events are characterized by rapidity gaps, which must be understood theoretically in order to correct for a rapidity gap survival probability.

These are the tasks and sub-tasks to be undertaken by the present proposal of networking:

ST 1.1 Event Generator for Diffractive Physics at LHC;

ST 2.1 Quarkonia physics in cold nuclear matter;

ST 2.2 Quarkonia physics in hot nuclear matter;

ST 2.4 Quarkonia Experimental Data Base;

T.3Diffractive Physics;

ST 3.1 Single/Double Diffractive Dissociation;

During the next years, many European physicists (experimentalists and theorists) will work in the topics described in the present document. The expected outcome and deliverables of the present networking will be :

1. International school for PhD students. Increase of the scientific cooperation between the participating groups and of the training of students (Ph.D and masters) in experiments and in theory; delivery month from start date: 18
2. Data base on quarkonia experimental results. Compilation of the existing experimental data on quarkonia production. This experimental data will be compiled in a data-base that will be accessible via internet (ST2.1, ST2.2, ST2.3); delivery month from start date: 30.
3. Common software tools. Development of common software tools, as event generator, to be used by both theorists and experimentalists (ST1.1 and ST2.2); delivery month from start date: 30.

For the next years, the LHC will be the unique laboratory in the world to create new phases of matter and address specific features of non-perturbative QCD processes.

The understanding of the QGP is of central importance for our comprehension of the strong interaction and of matter at extreme densities and temperatures. The production of quarkonia and their suppression (or enhancement) pattern provide one of the most promising probes to determine the properties of the QGP. LHC experiments will be able to address these issues in depth in the next years. European groups have been leaders in such experimental measurements since 1986 with the SPS program at CERN and have made important contributions to the research program at RHIC in the USA. With the LHC, this fundamental and cutting edge research is once again centred around Europe. With this proposal we request funding to be able to utilize efficiently these new European initiatives. These studies, at the scientific cutting edge, will be led by European groups from Denmark, France, Germany, Italy, Russia, Spain and Switzerland. The research will involve the development of advanced analysis techniques, novel theoretical methods and require massive distributed computations and thus drive the technology within these areas. This research provides crucial information about the properties of the QCD matter, the state of matter of the Universe about 10 microseconds after the Big Bang.

On the other hand, LHC will be a unique laboratory to study non-perturbative features of QCD like the diffractive production of quarkonia via the pomeron-induced process. Diffractive reactions, which will be characterized at LHC by forward scattered protons and by the presence of rapidity gaps, are poorly understood. The collaboration of theorists with experimentalists will allow for the identification of reaction channels to be measured by different experiments. One of the most promising channels will be the study of diffractive production of charmonia and bottomonia in both proton-proton and heavy ion ultra-peripheral collisions.

The present project will have a positive impact on the project of the CBM experiment at the FAIR facility in Darmstadt.