We study one-dimensional anisotropic XXZ spin-1/2 model with ferromagnetic sign of the coupling and z - z exchange constant Jz < Jxy.
We calculate damping of low-energy excitations with low energies due to their scattering from thermal excitation bath with temperature ω << T, taking into account nonzero curvature of the excitation spectrum. We calculate longitudinal spin-spin correlation function and find the shape of the spreading "wave packet".
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