Particularities of the NNLLA BFKL

TL;DR

This paper explores unique features of the BFKL approach at NNLLA, highlighting the need to modify derivation schemes due to complex amplitude behaviors and the importance of imaginary parts in unitarity relations.

Contribution

It identifies the peculiar properties of NNLLA BFKL and proposes changes to the derivation scheme to account for non-factorized amplitudes and imaginary parts.

Findings

Violation of simple factorized form in NNLLA

Necessity to include imaginary parts of amplitudes

Modified derivation scheme for NNLLA BFKL

Abstract

Peculiar properties of the BFKL approach in the next-to-next-to-leading logarithmic approximation (NNLLA) are discussed. In this approximation the scheme of derivation of the BFKL equation must be changed because of violation of the simple factorized form of amplitudes with multi-Reggeon exchanges and necessity to take into account imaginary parts of amplitudes in the unitarity relations.