Physical Review Letters
Computer Simulations of SU(N)⊗SU(N) Spin Systems in Two Dimensions
John B. Kogut, M. Snow, Michael Stone
Abstract
$\mathrm{SU}(N)\ensuremath{\bigotimes}\mathrm{SU}(N)$ spin systems in two dimensions are studied for $N=2, 3, \mathrm{and} 4$ on 10\ifmmode\times\else\texttimes\fi{}10, 20\ifmmode\times\else\texttimes\fi{}20, and 30\ifmmode\times\else\texttimes\fi{}30 lattices with use of Monte Carlo methods. Variant forms of the action are considered. In addition to crossover phenomena, unexpected first-order transitions in multidimensional phase diagrams are discovered. These transitions are related to the presence of ${Z}_{N}$ vortices which experience short-range interactions. Contrasts with $\mathrm{SU}(N)$ gauge theories in four dimensions are drawn.