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

We extend our previous study of magnetic monopole currents in the maximally Abelian gauge [1] to larger lattices at small lattice spacings (204 at β = 2.5 and 324 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 analytically calculable size distribution of small instantons. We also search for traces of Z(2) vortices in the Abelian projected fields; either as closed loops of ‘magnetic’ flux or through appropriate correlations amongst the monopoles. We find, by direct calculation, that there is no confining condensate of such flux loops. We also find, through the calculation of doubly charged Wilson loops within the monopole fields, that there is no suppression of the q = 2 effective string tension out to at distances of at least r ' 1.6/√K, suggesting that if there are any vortices they are not encoded in the monopole fields. PACS indices: 11.15.Ha, 12.38.Aw, 14.80.Hv.