The network for the heavy flavoured probes of deconfined QCD matter formed in heavy ion collisions at relativistic energies has the following objectives:

  • To improve and encourage interaction between theorists and experimentalist for the interpretation of the new LHC results on heavy flavoured observables and electroweak boson in heavy ion collisions.
  • To support young researchers working on this novel field of heavy flavour production in heavy ion collisions.
  • To ensure an effective scientific transition from LHC to FAIR future facility.
  • To support the soft diffractive community in nucleus-nucleus collisions.

Description of work and role of partners

At LHC both charmonia and bottomonia can be used, thus providing powerful probes for Quark Gluon Plasma studies. In fact, since the Υ (1S) state only dissolves significantly above the critical temperature, the spectroscopy of the Υ family at the LHC should reveal unique characteristics of the QGP. In addition to the centrality dependence of the Υ yield, the study of the Υ′/Υ ratio versus transverse momentum (Pt) is believed to be of crucial interest.
At the Large Hadron Collider, W and Z0 will provide the opportunity to observe them for the first time in heavy-ion collisions. They are considered as benchmarks, they have been suggested as ’standard-candles’ for luminosity measurements and as tools to ameliorate the detectors knowledge. A qualitative estimate of the formation and decay time of vector bosons with respect to the QGP formation and evolution will facilitate the comprehension of the physics processes involved. Weak bosons are formed early due to their large mass. Their decay time is by definition inversely proportional to their widths, that is 0.08 fm/c for the Z and 0.09 fm/c for the W. According to the most accepted picture of the QGP formation and evolution, at the LHC this state of matter would be formed after ∼ 1 fm/c of the initial hard interaction, would be quickly thermalized in approximately 0.1 fm/c, and might last ∼ 10 fm/c. In this representation, weak bosons are produced and decay before the QGP is formed.
This networking will support different manifestations to ensure an effective integration of the PhD students and young post-docs in the current physics analysis groups, in particular to assimilate the necessary background of the complex computing framework of the experiments.
A narrower interaction with the experimental physicists working on the new facilities in our field, like CMB experiment in the future FAIR facility, will allow for a successful “transmission” of new discoveries at LHC, for a smooth transition of part of the LHC heavy ion community to FAIR and for the brainstorming on new ideas of
physics analysis useful for both LHC and FAIR.
Finally, special attention will be paid to the community interested in the understanding of soft diffractive and electromagnetic processes in heavy ion collisions at LHC energies. This community, closed to the heavy ion community, has been financed by the IA HadronPhysics2 and our support via this network will be crucial for its survival. The understanding of diffractive production at LHC energies necessitates the understanding of electromagnetic processes. Diffractive 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.
The experimental heavy-ion groups, which are beneficiaries of the present work package, are outstanding experimental groups in the field of heavy-ion physics with the heavy flavour quark production. The Heidelberg group coordinates the theorists interested in the soft diffractive physics at LHC, in particular the diffractive production of hidden heavy flavour. Nantes, Clermont, Darmstadt and Padova groups coordinate the heavy flavour physics of the ALICE experiment, where about 25 European groups are involved. The Palaiseau group coordinates the heavy-ion programme of CMS experiments. These groups have been also working on phenomenological activities for the understanding of heavy flavour in heavy-ion collisions. A strong interaction between experimentalists and theorists is taking place via these experimental groups, in particular with the theorist groups in Bielefeld, Nantes, Santiago, Torino, Annecy and Saclay.

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