ONE-HOLE GREEN-FUNCTION, MOMENTUM DISTRIBUTION AND QUASI-PARTICLE WEIGHT OF THE U-]INFINITY-1D HUBBARD-MODEL

Starting from the known Lieb and Wu solution of the one-dimensional Hubbard model in the U --> infinity limit, we show how the spin-charge decoupling of the elementary excitations is responsible for several peculiar features in one-particle properties, such as momentum distribution, quasiparticle weight and the Green function. In particular we analyse in detail the structure of the one-hole Green function at half-filling, which has not been previously calculated by field theory methods due to the breakdown of conformal invariance. A rich structure is found with branch cut singularities at omega = +/- 2 sin kappa but no simple poles. The non-trivial dependence on the momentum of the hole allows for hole propagation although the analytic structure of G(kappa, omega) is quite different from that usually characterizing band insulators. These results provide a precise characterization of one-dimensional Mott insulators. The relationship between the branch cuts of the Green function and the finite-size scaling of the quasiparticle weight is also discussed together with its implications for the analysis of numerical data.