From quantum affine groups to the exact dynamical correlation function   of the Heisenberg model
  The exact form factors of the Heisenberg models $XXX$ and $XXZ$ have been recently computed through the quantum affine symmetry of $XXZ$ model in the thermodynamic limit. We use them to derive an exact formula for the contribution of two spinons to the dynamical correlation function of $XXX$ model at zero temperature. 
A.H. Bougourzi, M. Couture and M. Kacir