  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.
