Spin and energy correlations in the one dimensional spin- Heisenberg model

In this paper, we study the spin and energy dynamic correlations of the one-dimensional spin- Heisenberg model, using mostly exact diagonalization numerical techniques. In particular, observing that the uniform spin and energy currents decay to finite values at long times, we argue for the absence of spin and energy diffusion in the easy plane anisotropic Heisenberg model.