SCREENING MASSES IN SU(N) FROM WILSON RENORMALIZATION-GROUP

We apply a gauge invariant formulation of Wilson Renormalization Group (RG) to the computation of the Debye and transverse gluon masses in p ure gauge SU(N) at high temperature. Following the Hard Thermal Loop e ffective field theory as a guideline, we develop an approximation sche me to the exact evolution equations. The Debye mass receives sizable c orrections compared to the leading order perturbative result, mainly d ue to the infrared singular behavior in the transverse gluon sector. A non-vanishing mass for the transverse gluons is found, which acts as an infrared regulator though not efficiently enough as to restore the validity of perturbation theory. Indeed, discussing the role of higher dimensional operators, we show that the gauge coupling for the transv erse modes typically flows to non-perturbative values. (C) 1998 Elsevi er Science B.V.