Exact two-spinon dynamical correlation function of the Heisenberg model
  We derive the exact contribution of two spinons to the dynamical correlation function of the spin-1/2 Heisenberg model. For this, we use the isotropic limits of the exact form factors that have been recently computed through the quantum affine symmetry of the anisotropic Heisenberg model $XXZ$ 
A.H. Bougourzi, M. Couture and M. Kacir