GRASP colloquium by Prof. Dr. Pol Bernard Gossiaux

Quarkonium Production from small to large Ultra Relativistic hadronic systems

Prof. Dr. Pol Bernard Gossiaux, SUBATECH (IMT Atlantique, Nantes Université)

Abstract
Quarkonia production in ultrarelativistic systems can be a very good probe of various important apects of these systems as well as of the underlying theoretical approaches. In pp collisions, N(on) R(elativistic) QCD is usually considered as the correct scheme but relies on various long distance matrix elements which cannot be predicted by the fundamental theory. AA collisions lead to the creation a new state of matter where quarks and gluons would be deconfined as in the early universe: the so-called quark gluon plasma (QGP), predicted by lattice QCD calculations and confirmed by many experimental campaigns performed at SPS, RHIC and LHC colliders. Quarkonia are one of the “hard probes” candidates that allow a direct investigation of QGP properties, as they they are formed of heavy quarks which are still able to bind in hot and dense matter. In this context, theoretical descriptions range from statistical hadronization to pretty involved “open quantum system” approaches.

While LHC has been running either heavy ions or pp collisions up to now, future experiments are considering to perform a scan through various light to heavy systems. It is hence a challenge for theory to gather the correct ingredients be able to describe quarkonium physics in the same conditions. In this seminar, I will introduce the general context of QGP formation in URHIC and then review some of the experimental observables pertaining to quarkonia production as well as their physical interpretation. I will then describe recent progress performed under the umbrella of our EPOS4-HQ Monte-Carlo generator developed in Nantes, both the production in small and large systems, in connection with the open heavy flavor observables.