A Study of the Gluon Ladder in Diffractive Processes
  The solution to the non-forward BFKL equation in the Leading Logarithmic approximation is expressed in terms of a sum of iterations of its kernel directly in transverse momentum and rapidity space. Several studies of the non-forward solution are performed both at the level of the gluon Green's function and for a toy cross-section, including an analysis of the diffusion properties as found in this approach. The method developed in this paper allows for a direct inspection of the momenta in the BFKL ladder, and can be applied to solving the non-forward BFKL equation to next-to-leading logarithmic accuracy, when the corresponding kernel is available. 
Jeppe R. Andersen (Cambridge U.), Agustin Sabio Vera (Hamburg U.,   Inst. Theor. Phys. II)