Reggeon cuts in QCD amplitudes with negative signature

TL;DR

This paper investigates Reggeon cuts with negative signature in QCD amplitudes, highlighting their emergence at NNLLA, analyzing their Feynman diagrams, and calculating their contributions at two- and three-loop levels, which complicates BFKL equation derivation.

Contribution

It identifies and computes the contributions of Reggeon cuts with negative signature in QCD at NNLLA, advancing understanding of their impact on the BFKL framework.

Findings

Reggeon cuts with negative signature appear at NNLLA.

Feynman diagrams responsible for these cuts are identified.

Cut contributions are calculated at two- and three-loop levels.

Abstract

Reggeon cuts in QCD amplitudes with negative signature are discussed. These cuts appear in the next-to-next-to-leading logarithmic approximation (NNLLA) and greatly complicate the derivation of the BFKL equation. Feynman diagrams responsible for appearance of these cuts are indicated and the cut contributions are calculated in the two- and three-loop approximation.