Exact two-spin dynamic structure factor of the one-dimensional s=1/2 Heisenberg-Ising antiferromagnet

A. Hamid Bougourzi, Michael Karbach, Gerhard Müller

The exact 2-spinon part of the dynamic spin structure factor $S_{xx}(Q,\omega )$ for the one-dimensional $s$=1/2 $XXZ$ model at $T$=0 in the antiferromagnetically ordered phase is calcul…