New Easy-Plane CP<sup><em>N</em>−1</sup> Fixed Points

Abstract

We study fixed points of the easy-plane CPN−1 field theory by combining quantum Monte Carlo simulations of lattice models of easy-plane SU(N) superfluids with field theoretic renormalization group calculations, by using ideas of deconfined criticality. From our simulations, we present evidence that at small N our lattice model has a first-order phase transition which progressively weakens as N increases, eventually becoming continuous for large values of N. Renormalization group calculations in 4−ε dimensions provide an explanation of these results as arising due to the existence of an Nep that separates the fate of the flows with easy-plane anisotropy. When N < Nep, the renormalization group flows to a discontinuity fixed point, and hence a first-order transition arises. On the other hand, for N > Nep, the flows are to a new easy-plane CPN−1 fixed point that describes the quantum criticality in the lattice model at large N. Our lattice model at its critical point, thus, gives efficient numerical access to a new strongly coupled gauge-matter field theory.