PHASE-TRANSITION AND DYNAMICAL-PARAMETER METHOD IN U(1) GAUGE-THEORY

Monte Carlo simulations of the 4-dimensional compact U(1) lattice gaug e theory in the neighborhood of the transition point are made difficul t by the suppression of tunneling between the phases, which becomes ve ry strong as soon as the volume of the lattice grows to any appreciabl e size. This problem can be avoided by making the monopole coupling a dynamical variable. In this manner one can circumvent the tunneling ba rrier by effectively riding on top of the peaks in the energy distribu tion which meet for sufficiently large monopole coupling. Here we pres ent an efficient method for determining the parameters needed for this procedure, which can thus be implemented at low computational cost al so on large lattices. This is particularly important for a reliable de termination of the transition point. We demonstrate the working of our method on a 16(4) lattice. We obtain an equidistribution of configura tions across the phase transition even for such a relatively large lat tice size.