't Hooft-Polyakov monopoles and Dirac strings in the 3D Georgi-Glashow model

After having roughly scanned the phase structure of the 3D Georgi-Glashow model on an 83 lattice, we investigate whether the vacuum supports an underlying (semiclassical) (anti)monopole structure. Starting from Monte Carlo generated equilibrium configurations, a Langevin-type relaxation procedure is applied in order to freeze out the quantum fluctuations. As expected, from continuum considerations, we find quasi stable plateaus in the action corresponding to pairs of monopoles-antimonopoles (manti m). These excitations are localized in space (although in general not spherical symmetric) and carry a magnetic charge of ±1. Our data show that the density of these pairs drops very sharply at the Higgs phase transition. In addition we observe stable abelian Dirac strings, which arise from manti m pairs annihilating through the boundaries. (orig.)