Phases of the two-band model of spinless fermions in one dimension

Abstract

We study the two-band model of spinless fermions in one dimension for weak repulsive interactions. In this case, the model is equivalent to the weakly interacting spinless two-leg ladder. We obtain analytic expressions for the superconducting pairing correlation function and the charge density correlation function, which show, that a finite interchain hopping t_p results in dominant superconductivity for repulsive interactions (for vanishing t_p, we recover previous results). We furthermore find that the transition from the superconducting phase to the usual one-dimensional (Luttinger) metal at large doping occurs via a mixed phase, where superconducting pairs are formed in the bonding band only. We give the phase diagram as a function of temperature and doping.