Check of the Bootstrap Conditions for the Gluon Reggeization

The property of gluon Reggeization plays an essential role in the derivation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at high energy $\sqrt s$ in perturbative QCD. This property has been proved to all orders of perturbation theory in the leading logarithmic approximation and it is assumed to be valid also in the next-to-leading logarithmic approximation, where it has been checked only to the first three orders of perturbation theory. From $s$-channel unitarity, however, very stringent ``bootstrap'' conditions can be derived which, if fulfilled, leave no doubts that gluon Reggeization holds.