Tricritical Phenomena in a Z(3) Lattice Gauge Theory
  The Z(3) gauge model with double plaquette representation of the action on a generalized Bethe lattice of plaquettes is constructed. It is reduced to the spin-1 Blume-Emery-Griffiths (BEG) model. An Ising-type critical line of a second-order phase transition ending in the tricritical point is found. 
N.S. Ananikian and R.R. Shcherbakov