Study of the 2-d CP(N-1) models at \theta=0 and \pi
  We present numerical results for 2-d CP(N-1) models at \theta=0 and \pi obtained in the D-theory formulation. In this formulation we construct an efficient cluster algorithm and we show numerical evidence for a first order transition for CP(N-1\geq 2) models at \theta = \pi. By a finite size scaling analysis, we also discuss the equivalence in the continuum limit of the D-theory formulation of the 2-d CP(N-1) models and the usual lattice definition. 
B.B. Beard, M. Pepe, S. Riederer, U.J. Wiese