Singular gauge potentials and the gluon condensate at zero temperature

We consider a new cooling procedure which separates gluon degrees of freedom from singular center vortices in SU(2) LGT in a gauge invariant way. Restricted by a cooling scale $kappa^4/sigma^2$ fixing the residual SO(3) gluonic action relative to the string tension, the procedure is RG invariant. In the limit $kappa to 0$ a pure Z(2) vortex texture is left. This {it minimal} vortex content does not contribute to the string tension. It reproduces, however, the lowest glueball states. With an action density scaling like $a^4$ with $beta$, it defines a finite contribution to the action density at T=0 in the continuum limit. We propose to interpret this a mass dimension 4 condensate related to the gluon condensate. Similarly, this vortex texture is revealed in the Landau gauge.