We discuss the pole structure of the BFKL equation in the complex angular momentum plane. We argue that beyond the leading order, the proper
framework for the BFKL dynamics is the Bethe–Salpeter equation. The Bethe–Salpeter equation was derived for describing evolution of the bound states and can provide a natural framework for the propagation of the bound state of two reggeized gluons.
The Bethe–Salpeter approach to the BFKL dynamics sheds light on the internal structure of the BFKL eigenvalue beyond the leading order
revealing the way the BFKL kernel with hermitian separability can result into the higher-order BFKL eigenvalue, where the hermitian separability is absent.