Finite-size effects in a non-half-filled Hubbard chain

Abstract

The finite-size effects in the spectrum of a Hubbard chain are obtained for both the repulsive and attractive cases. It is shown that the finite-size corrections-similar to the case of a Heisenberg chain or Bose gas-are nonanalytic unless some conditions are imposed on the chemical potential, magnetic field and chain length. If these conditions are met, the spectrum shows a similar tower structure as expected in conformal theories, although the model in general is not conformally invariant. In the special case when the two fermi velocities are equal, the model is conformally invariant with c=2, the indices are similar to the Gaussian form and there are four marginal operators.