Gauge invariant effective action for high-energy processes in QCD

TL;DR

This work constructs a gauge-invariant effective action for high-energy QCD that couples physical gluons to reggeized gluons within quasi-multi-Regge kinematics. By employing Wilson-line (contour) methods and a rapidity-interval decomposition, it generalizes to multi-gluon final states and derives a reggeon action at tree level. The formalism yields gauge-invariant induced vertices, a central-rapidity production framework, and a Reggeon-calculus capable of incorporating loop corrections and unitarity constraints, with clear connections to BFKL/BKP dynamics. It also outlines the potential for extensions to quantum gravity, illustrating the broader utility of the approach for reggeized field theories.

Abstract

The Born amplitudes for quasi-multi-Regge kinematics of produced gluons are constructed in accordance with the Feynman rules including apart from usual Yang-Mills vertices also an infinite number of induced vertices. The new vertices describe the interaction of physical gluons produced in direct channels with the reggeized gluons propagating in crossing channels. The nonlinear gauge invariant effective action reproducing these Feynman rules is constructed with the use of the Wilson contour integrals. After integrating over the physical degrees of freedom the reggeon action is derived.