Field strength correlator and an infrared fixed point of the Wilsonian exact renormalization group equations

The correlator of two field strengths is computed from an effective action for Yang Mills theories, which contains both gluons and an auxiliary antisy mmetric tensor field for the field strength as local variables. This action allows to relate explicitly many different approaches to confinement, and is computed using Wilsonian renormalization group equations with the bare Y ang Mills action as starting point. Due to the inclusion of a higher dimens ional operator in the ghost sector the running gauge coupling becomes vanis hingly small at a critical scale k(c), and the resulting low energy action resembles the action of a confining string theory proposed by Polyakov.