Charm degrees of freedom above deconfinement

The phase diagram of strongly interacting matter described by Quantum Chromodynamics is mainly explained through two processes, chiral symmetry breaking and deconfinement. It is now known from lattice studies that deconfinement of quark degrees of freedom happen at temperature Tc when the chiral symmetry is approximately restored. However the so called quark gluon plasma phase(QGP) formed is still strongly interacting and the nature of quasiparticles in the plasma are still not well understood. We use heavy charm quarks as a probe to understand the dominant quasi-particles in the QGP. By using fluctuations of charm quantum number and its correlations with other conserved numbers in a hot QCD medium, we investigate the dominant degrees of freedom that carry charm quantum number. We observe that quark degrees of freedom start to appear only at 1.2 Tc. We also support our findings from our independent study of the screening masses of charm hadron like excitations.