Finite temperature QCD sum rules and phase transitions in hadronic matter

The finite temperature QCD sum rules are discussed as a method of investigation of the spectrum of hot hadronic matter. The analysis of the sum rules in vector and axial vector channels reveals a qualitative rearrangement of the spectrum in the temperature interval T = 130 - 150 MeV. The sum rules indicate that the restoration of the chiral symmetry cannot precede deconfinement and that the temperature evolution of the effective pion constant fπ(T) is determined mainly by the temperature behaviour of the condensates of quark and gluon fields. 13 refs.; 1 figure