Subleading Reggeons in Deep Inelastic Diffractive Scattering at HERA
  The contribution of subleading reggeons to the diffractive structure function ${dF_{2}^D / dx_{\funp} dt}$ is estimated from the soft physics data. This contribution leads in a natural way to the violation of the factorization property of the diffractive structure function. 
K.Golec-Biernat and J.Kwiecinski