Monopole condensation and the lattice-quantum-chromodynamics crossover

We propose the condensation of dynamical monopoles and their strings as the mechanism responsible for the rapid crossover from weak to strong coupling in SU(2) lattice gauge theory. By adding to the Wilson action a chemical potential for monopole formation, we are able to study the crossover in an extended phase plane. We find a critical value for the potential, related to the transition in a dual Ising model, above which monopoles are absent. Support for this picture is garnered from Monte Carlo simulations.