Lattice models for non-Fermi-liquid metals

We present two two-dimensional lattice models with non-Fermi-liquid metallic phases. We show that the low-energy physics of these models is exactly described by a Fermi sea of fractionalized quasiparticles coupled to a fluctuating U(1) gauge field. In the first model, the underlying degrees of freedom are spin-1/2 fermions. This model demonstrates that electrons can in principle give rise to non-Fermi-liquid metallic phases. In the second model, the underlying degrees of freedom are spinless bosons. This model provides a concrete example of a (non-Fermi-liquid) Bose metal. With little modification, it also gives an example of a critical U(1) symmetric spin liquid.