The compatibility of the gluon Reggeization with the s-channel unitarity

Recently the non-forward BFKL kernel for interaction of two Reggeized gluons in the antisymmetric colour octet state in the t-channel was obtained in the next-to-leading order. It gives the possibility to check in this order the bootstrap condition for this kernel, appearing as the requirement of the compatibility of gluon Reggeization with the s-channel unitarity.