Gauge – invariant field – strength correlators in pure

We study by numerical simulations on a lattice the behaviour of the gauge–invariant two– point correlation functions of the gauge–field strengths across the deconfinement phase transition, both for the pure–gauge SU(3) theory and for full QCD with two flavours. Quenched data agree within errors with previous determinations, but have much higher statistics. A best–fit analysis of the data has been performed, both for the quenched and the full–QCD case, showing that the electric gluon condensate drops to zero at the deconfining phase transition. (PACS codes: 12.38.Gc, 11.10.Wx) Partially supported by MIUR (Italian Ministry of the University and of Scientific and Technological Research) and by the INTAS contract 00–0110.