QCD instantons at finite temperature (I). Gluonic interactions and the fermion determinant

This is the first in a series of papers devoted to instanton-induced effects at non-zero temperatures. The main points will be the restoration of the chiral symmetry and the modification of the various correlation functions with increasing temperature. In this paper we investigate the temperature dependence of the gluonic and the quark-induced pseudo-particle interaction. We find that the gluonic interaction becomes much more long ranged, whereas the quark-induced interaction becomes exponentially short ranged.