Z₂ monopoles, vortices, and the deconfinement transition in mixed action SU(2) gauge theory

Abstract

Adding separate chemical potentials λ and γ for Z₂ monopoles and vortices, respectively, in the Villain form of the mixed fundamental-adjoint action for the SU(2) lattice gauge theory, we investigate their role in the interplay between the deconfinement and bulk phase transitions using Monte Carlo techniques. Setting λ to be nonzero, we find that the line of deconfinement transitions is shifted in the coupling plane but it behaves curiously also like the bulk transition line for large enough adjoint coupling, as for λ=0. In a narrow range of couplings, however, we find separate deconfinement and bulk phase transitions on the same lattice for nonzero and large λ, suggesting the two to be indeed coincident in the region where a first order deconfinement phase transition is seen. In the limit of large λ and γ, we obtain only lines of second order deconfinement phase transitions, as expected from universality.