Results on the nature of charm degrees of freedom in strongly interacting hot matter are presented. These are based on lattice QCD calculations of the second-and fourth-order cumulants of charm fluctuations, and their correlations with net baryon number, electric charge, and strangeness fluctuations. It is shown that below the chiral crossover temperature, T_c, the thermodynamics of charm can be very well understood in terms of charmed hadrons. Above T_c, however, charm quark-like excitations emerge as new degrees of freedom contributing to the partial charm pressure. Nonetheless, up to temperatures as high as 175 MeV, charmed hadron-like excitations significantly contribute to the partial charm pressure. The implications of these findings for understanding the nature of interactions inside the Quark-Gluon Plasma are discussed . Additionally, evidence is presented for the not-yet-discovered charmed hadrons below the chiral crossover by comparing predictions of a hadron resonance gas with lattice QCD simulations.
Hybrid access via ZOOM:
https://lmu-munich.zoom.us/j/98457332925?pwd=TWc3V1JkSHpyOTBPQVlMelhuNnZ1dz09
Meeting ID: 984 5733 2925
Passcode: 979953
Peter Thirolf (LMU) / Norbert Kaiser (TUM)