Bethe ansatz for two-magnon bound states in anisotropic magnetic chains of arbitrary spin

Abstract
The two-magnon spectra in anisotropic magnetic chains of arbitrary spin are derived by an elementary method which is an extension of Bethe’s original ansatz for spin-(1/2) systems. Applications are presented for quantum spin chains with uniaxial or Ising Anisotropy as well as chains with quartic exchange interactions. The nature of certain collective modes emerging in a 1/n expansion is also clarified.