  We describe the zero temperature phases and phase boundaries of an effective
lattice model for frustrated, easy-plane, spin S=1/2 quantum antiferromagnets.
The model contains states with Neel and bond-centered charge order and
fractionalization in different limiting regimes, and we describe how these
orders compete at intermediate coupling. The complex Berry phase terms render
this model unsuitable for direct simulation; however, a duality mapping leads
to a model of interacting current loops with positive weights, which is then
studied by Monte Carlo simulations.
