Pomeron exchange and t-dependence of the scattering amplitude
  Constraints on the t-dependence of the hadronic scattering amplitude at asymptotic energies are derived by considering the exchange of the Pomeron, as a Regge pole, between off-shell gluons. Covariant reggeization ensures pure spin alpha exchange, where alpha is the Regge trajectory of the Pomeron. The structure of the amplitude, as a function of t, has been derived without a specific choice for the partonic wave functions of the hadrons. New terms appear, with respect to the standard approach, and allow to describe non trivial properties of the diffraction cone in agreement with experimental data, as shown in a specific example. 
F. Paccanoni