Glueball dynamics in the hot plasma

We discuss the glueball contribution to the equation of state (EoS) of hot gluon matter below and above $ T_{c}$ . We show that the strong variation of the masses of the scalar and pseudoscalar glueballs near $ T_{c}$ is determining the thermodynamics of the SU(3) gauge theory. We provide arguments to justify that these glueballs become massless at $ T_{G}\approx 1.1 T_{c}$, a phenomenon which is crucial to understand the mysterious behavior of the trace anomaly found in lattice calculations