Some universal properties of the string breaking

Abstract

In gauge systems coupled to matter, the static potential flattens out at a scale where the confining string breaks by formation of a dynamical pair of particles. Surprisingly, such a breaking is invisible in Wilson loops even when the inter-charge separation is much larger than the flattening scale. Observing string breaking also requires using different operators. A known string mechanism provides us with a simple explanation, leading to the area law for large Wilson loops, as observed in most gauge models coupled to whatever kind of matter. It is also pointed out that in a simple 3D Z_2 gauge-Higgs model, once reformulated in terms of Fortuin Kasteleyn clusters, this peculiar behaviour of the Wilson operator can be ascribed to non-trivial linking of a percolating cluster to the Wilson loop. Some numerical tests on this model are also presented.