Dyson equation for the real two-time commutator retarded one-magnon Green function of the ferromagnetically polarized XX chain is suggested following the Plakida-Tserkovnikov algorithm. Starting from this result a low-temperature integral representation for the corresponding magnon self energy is obtained by the truncated form factor expansion however without any resummations. Within the suggested approach the low-temperature asymptotics of the transverse dynamical structure factor may be readily studied. Some obtained line shapes are presented.
Categories: cond-mat.str-el