We analyze interacting lattice fermions with anisotropic hopping amplitudes. Calculating the linear response of the momentum distribution function, we find that one-dimensional Luttinger liquid phases are unstable with respect to arbitrarily small transverse hopping, even if the interaction is strong. This instability is expected to signal the formation of states with broken symmetry in the strongly anisotropic regime.

• Received 4 May 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.1703