“…In principle, also BA allows to determine dynamical correlation functions, however calculating the corresponding matrix elements is highly non-trivial and progress has been made only recently. By now analytic expressions for dynamical spin correlation functions are available for the two- 27,28,29 and the fourspinon sector 30,31,32,33 at ∆ = 1, h = 0 and T = 0. In addition, determinant approaches 34,35 allow for numerical treatment of two- 36,37,38 and many-spinon 39,40 states of the XXZ chain in finite magnetic fields, at T = 0.…”