Gluon Regge trajectory at two loops from Lipatov's high energy effective action

TL;DR

This paper derives the two-loop gluon Regge trajectory using Lipatov's high energy effective action, employing a gauge invariant regularization and Mellin-Barnes techniques, confirming previous results and validating the theoretical framework.

Contribution

It provides a novel derivation of the two-loop gluon Regge trajectory within Lipatov's effective action framework, using a new regularization and subtraction method.

Findings

Agreement with previous two-loop results

Validation of the effective action and subtraction framework

Successful computation of master integrals using Mellin-Barnes techniques

Abstract

We present the derivation of the two-loop gluon Regge trajectory using Lipatov's high energy effective action and a direct evaluation of Feynman diagrams. Using a gauge invariant regularization of high energy divergences by deforming the light-cone vectors of the effective action, we determine the two-loop self-energy of the reggeized gluon, after computing the master integrals involved using the Mellin-Barnes representations technique. The self-energy is further matched to QCD through a recently proposed subtraction prescription. The Regge trajectory of the gluon is then defined through renormalization of the reggeized gluon propagator with respect to high energy divergences. Our result is in agreement with previous computations in the literature, providing a non-trivial test of the effective action and the proposed subtraction and renormalization framework.