  We study the phase diagram of the frustrated XY model on the honeycomb
lattice by using accurate correlated wave functions and variational Monte Carlo
simulations. Our results suggest that a spin-liquid state is energetically
favorable in the region of intermediate frustration, intervening between two
magnetically ordered phases. The latter ones are represented by classically
ordered states supplemented with a long-range Jastrow factor, which includes
relevant correlations and dramatically improves the description provided by the
purely classical solution of the model. The construction of the spin-liquid
state is based on a decomposition of the underlying bosonic particles in terms
of spin-1/2 fermions (partons), with a Gutzwiller projection enforcing no
single occupancy, as well as a long-range Jastrow factor.
