PHASE DIAGRAM OF THE GAUGE INVARIANT TWO SPECIES ISING MODEL

Abstract

We study the phase diagram of a Z(2) Higgs-gauge model with two species of Ising matter in D=2 and D=3. Differently from the case with only one Ising species, this model exhibits a transition also at zero gauge coupling. Loop expansions and mappings on the 8-vertex and the Ashkin–Teller models are used to study the nature of the transitions in the extreme regions of the phase diagram. Relevant differences with respect to the case of one species of Ising spins are found.