Calculation of Reggeon Vertices in QCD

TL;DR

This work presents a direct, region-based method to compute Reggeon–particle vertices in QCD at next-to-leading order. By decomposing two-particle t-channel exchange diagrams into a universal central region and fragmentation regions attached to external particles, the authors derive a practical prescription to reconstruct Reggeized-gluon and Reggeized-quark vertices from known LO quantities and universal trajectory corrections. They provide explicit NLO results for the Quark–Quark–Reggeized-gluon, Gluon–Gluon–Reggeized-gluon, and Gluon–Quark–Reggeized-quark vertices, with the latter being new, and confirm consistency with established BFKL/NLO structure. The method isolates universal, process-independent contributions and is applicable to transitions between particle groups with fixed invariant masses, offering a valuable tool for high-energy QCD phenomenology and the NLO BFKL kernel.

Abstract

The method of calculation of effective vertices of interaction of the Reggeized gluon and quark with particles in QCD in the next-to-leading order is developed. The method is demonstrated in the case of already known vertices of both gluon-gluon and quark-quark transitions in the scattering of gluons and quarks on the Reggeized gluon. It is used for the calculation of the gluon-quark transition in the scattering on the Reggeized quark.

Figures (1)

• Figure 1: Schematic representation of diagrams with two-particle state in the $t$-channel for the process $A + B \rightarrow A' + B'$ at NLO.