Critical properties of the N-color London model
  The critical properties of $N$-color London model are studied in $d=2+1$ dimensions. The model is dualized to a theory of $N$ vortex fields interacting through a Coulomb and a screened potential. The model with N=2 shows two anomalies in the specific heat. From the critical exponents $\alpha$ and $\nu$, the mass of the gauge field, and the vortex correlation functions, we conclude that one anomaly corresponds to an {\it inverted} \xy fixed point, while the other corresponds to a \xy fixed point. There are $N$ fixed points, namely one corresponding to an inverted \xy fixed point, and $N-1$ corresponding to neutral \xy fixed points. This represents a novel type of quantum fluid, where superfluid modes arise out of charged condensates. 
J. Smiseth, E. Smorgrav, A. Sudbo