Debye mass at the QCD transition in the PNJL model

We consider colour-electric screening as expressed by the quark contribution to the Debye mass calculated in a PNJL model with emphasis on confining and chiral symmetry breaking effects. We observe that the screening mass is entirely determined by the nonperturbative quark distribution function and temperature dependent QCD running coupling. The role of the gluon background (Polyakov loop) is to provide strong suppression of the number of charge carriers below the transition temperature, as an effect of confinement, while the temperature dependent dynamical quark mass contributes additional suppression, as an effect of chiral symmetry breaking. An alternative derivation of this result from a modified kinetic theory is given, which allows for a slight generalization and explicit contact with perturbative QCD. This gives the possibility to gain insights into the colour screening mechanism in the region near the QCD pseudocritical temperature and to provide a guideline for the interpretation of lattice QCD data.