Miller, J. (2009), "The Schwinger-Dyson equation on Pomeron loop summation and renormalization", Nucl. Phys. A, 836: 119-135.
Abstract: The solution to the Schwinger–Dyson equation that describes the summation over Pomeron loop diagrams is derived. The solution is a closed expression which splits into two parts. The first leads directly to the renormalization of the BFKL Pomeron, and the second contribution is equivalent to non-interacting Pomerons with renormalized vertices. Thus a closed expression is derived for the sum over Pomeron loop diagrams in the perturbative QCD approach, which preserves unitarity.