Monopole clusters , Z ( 2 ) vortices and confinement in SU ( 2 ) . UKQCD

We extend our previous study of magnetic monopole currents in the maximally Abelian gauge [1] to larger lattices at small lattice spacings (20 4 at β = 2.5 and 32 4 at β = 2.5115). We confirm that at these weak couplings there continues to be one monopole cluster that is very much longer than the rest and that the string tension, K, is entirely due to it. The remaining clusters are compact objects whose population as a function of radius follows a power law that deviates from the scale invariant form, but much too weakly to suggest a link with the instanton size distribution. We also study higher charged monopole Wilson loops as a probe of an underlying Z(2) vor-tex confinement mechanism. We find the magnetic flux to be Coulombic on the length scales probed (r ≃ 1.6/ √ K), so that if there is an underlying vortex structure, it is not manifesting itself on the natural length scale.