Monte Carlo analysis of the SU(2) × U(1) and U(2) lattice gauge theories at different space-time dimensionalities

Using Monte Carlo simulations the SU(2)×U(1) lattice gauge theory has been analyzed, which is equivalent for the Wilson action to a U(2) theory, at space-time dimensionalities from d=3 to 5. It has been shown that there exist first-order phase transitions for both d=4 and d=5. A monopole-condensation mechanism seems to be responsible for these phase transitions. At d=3 no phase transitions have been detected. © 1986.