Z2monopoles, vortices, and the deconfinement transition in mixed action SU(2) gauge theory

Abstract

Adding separate chemical potentials $\ensuremath{\lambda}$ and $\ensuremath{\gamma}$ for ${Z}_{2}$ 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 $\ensuremath{\lambda}$ 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 $\ensuremath{\lambda}=0.$ In a narrow range of couplings, however, we find separate deconfinement and bulk phase transitions on the same lattice for nonzero and large $\ensuremath{\lambda},$ suggesting the two to be indeed coincident in the region where a first order deconfinement phase transition is seen. In the limit of large $\ensuremath{\lambda}$ and $\ensuremath{\gamma},$ we obtain only lines of second order deconfinement phase transitions, as expected from universality.