Common working group meeting of WG2 and WG3 of the COST Action CA15213 THOR and GDRE.
The meeting will discuss present issues of the open and hidden charm meson produced in relativistic heavy ion collisions. It became evident over the last years that open and closed charm mesons are the most sensitive probe to study the properties of a quark gluon plasma, created in heavy ion collisions at ultrarelativisitc energies. Heavy quarks interact with the plasma but the plasma does not bring them to an equilibrium. Therefore the modification of the properties of heavy quarks reflects their interaction with the plasma. We intend to discuss the issues which are currently under debate: The production of heavy quarks in heavy ion collisions, their interaction mechanism with the plasma particles, their hadronisation and the possible existence of heavy mesons in the plasma close to Tc.