Tensor renormalization group analysis of CP(N-1) model
  We apply the higher-order tensor renormalization group to the lattice CP($N-1$) model in two dimensions. A tensor network representation of the CP($N-1$) model in the presence of the $\theta$ term is derived. We confirm that the numerical results of the CP(1) model without the $\theta$ term using this method are consistent with that of the O(3) model which is analyzed by the same method in the region $\beta \gg 1$ and that obtained by the Monte Carlo simulation in a wider range of $\beta$. The numerical computation including the $\theta$ term is left for future challenges. 
Hikaru Kawauchi and Shinji Takeda
hep-lat