QUASI-PARTICLE CURRENTS IN ONE-DIMENSIONAL CORRELATED MODELS

We consider current carrying states in a one-dimensional system of interacting electrons. New exact results for the Hubbard model and the bosonization method are exploited. We find that away from half-filling, both spin and charge excitations carry currents which are proportional to their momenta in most cases. Being in qualitative agreement with a single particle picture of the noninteracting 1-d Fermi gas, this result contradicts the spin-charge separation concept as it is usually derived from bosonization concepts and strong coupling arguments. We show that the bosonization procedure can be reconciled with the exact one (in the weak interaction limit) if spectrum parabolicity is taken into account. Both the current and the Hamiltonian acquire nonlinear cross-terms between the two channels. Finally, we study current carrying excited states for the Hubbard model in the presence of a magnetic field flux. In addition to the known diamagnetic contribution, we find a temperature-dependent orbital paramagnetic contribution from both singlet and triplet excited slates. This paper extends and detals the recent statements formulated by P. Nozieres and the present authors.