Projection operator approach to spin diffusion in the anisotropic Heisenberg chain at high temperatures.

摘要: Spin transport in the anisotropic Heisenberg chain is typically investigated theoretically with respect to finiteness of coefficients only. Assuming their at high temperatures, we develop a concrete quantitative picture diffusion constant/(dc-)conductivity as function both anisotropy parameter Δ and spin quantum number s, going beyond most commonly considered case s=1/2. Using this picture, enable comparison finite from complementary theoretical methods on level, having more significance than alone. Our method essentially based an application time-convolutionless projection operator technique current autocorrelations. This technique, although being perturbation theory Δ, found be applicable, even if not small. finding supports applicability wider class strongly interacting many-particle systems.