  The correlator of two field strengths is computed from an effective action
for Yang Mills theories, which contains both gluons and an auxiliary
antisymmetric 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
Yang Mills action as starting point. Due to the inclusion of a higher
dimensional operator in the ghost sector the running gauge coupling becomes
vanishingly small at a critical scale k_c, and the resulting low energy action
resembles the action of a confining string theory proposed by Polyakov.
