Universality and the deconfinement phase transition in SU(2) lattice gauge theory Original Research Article

We study the three-dimensional fundamental-adjoint SU(2) lattice gauge theory at non-zero temperatures by Monte Carlo simulations. On an 83 × 2 lattice, at βA = 1.1, where βA is the adjoint coupling, we find no evidence of any transition at the location of a previously known bulk phase transition around β = 1.33. Moreover, the deconfinement transition at βA = 1.1 occurs at β = 1.20 and is of first order for βA ⩾ 1.1, thus implying a change of universality class from that of the Wilson action at βA = 0. Computations of the plaquette susceptibility and the temporal and spatial Polyakov loops on 83 × 4 and 163 × 8 lattices at βA = 1.1 further support these conclusions and suggest that the previously claimed bulk transition around β = 1.33 is, in fact, the first-order deconfinement transition. Simulations at larger βA and the measurements of the mass gaps from the correlation functions of temporal and spatial Polyakov loops also confirm the temperature dependent nature of the above transition. The consequences of our results on universality are discussed.