Temperature dependence of charge transport in the half-filled one-dimensional Hubbard model

The use of hydrodynamic transport theory seems to indicate that the charge diffusion constant D of the one-dimensional (1D) half-filled Hubbard model, whose Drude weight vanishes, diverges for temperature T > 0, which would imply anomalous superdiffusive charge transport. Here the leading term of that constant is derived for low finite temperatures k(B)T/Delta(eta) << 1 where Delta(eta) is the Mott-Hubbard gap. It only diverges in the T -> 0 limit, being finite and decreasing upon increasing T within the k(B)T/Delta(eta) << 1 regime. Our exact results both provide valuable physical information on a complex quantum problem and bring about the interesting unsolved issue of how charge transport evolves from normal diffusive for k(B)T /Delta(eta) << 1 to anomalous superdiffusive in the k(B)T -> infinity limit.