‘‘Confinement’’ in the one-dimensional Hubbard model: Irrelevance of single-particle hopping

We demonstrate, by direct use of the asymptotic Green's functions of Korepin and Ren, that the one-dimensional repulsive U Hubbard model has the property of ``confinement,'' in that weak interchain coupling does not cause coherent particle motion in the transverse direction at absolute zero. Implications for real one-dimensional systems and for the two-dimensional Hubbard model are discussed.