Breakdown of quasiparticle picture in the low-density limit of the 1D Hubbard model

摘要

Using the finite-size scaling of results obtained by exact diagonalization, we study the low-density limit of the one-dimensional Hubbard model. Calculating the quasiparticle weight, we demonstrate that for a given particle number N and system size L, there always exists a crossover point U(sub c) separating the Fermi-liquid (U < U(sub c)) and non-Fermi-liquid (U > U(sub c)) regimes (U is the Hubbard repulsion). We find that for a fixed N, U(sub c) is inversely proportional to L, keeping U(sub c)L/t constant (with t as the hopping integral), as L is large enough. It follows that in the low-density (in fact vanishing density) limit L (yields) (infinity), U(sub c) (yields) 0, so the system is always in non-Fermi-liquid regime as long as U > 0. We show that our numerical results are consistent with the Bethe ansatz solution. (author). 11 refs, 3 figs. (Atomindex citation 26:049194)