S-matrix and productions amplitudes in high energy QCD

S Bondarenko,S Pozdnyakov

doi:10.1016/j.physletb.2018.06.054

Abstract

In this note we discuss a generalization of the Lipatov's effective action approach, [1,2], for the case of description of gluon and quark production amplitudes in the quasi-multi-Regge kinematics. Following to [3], we define the S-matrix elements of high energy QCD processes in this kinematics and discuss applications of the obtained results.

Highlights

The Lipatov’s effective action approach, [1,2], which introduces in QCD the reggeized gluon fields as new degrees of freedom, is widely used in the calculation of the high energy QCD scattering amplitudes, [4]
We extend the formalism in order to include in the vertices of real particles production, i.e. the vertices of interaction of the reggeons with asymptotic gluon and quark fields
In this note we extended the formalism of the Lipatov’s effective action for the case of calculation of production amplitudes in quasi-multi-Regge kinematics at high energy

Summary

Introduction

The Lipatov’s effective action approach, [1,2], which introduces in QCD the reggeized gluon fields as new degrees of freedom, is widely used in the calculation of the high energy QCD scattering amplitudes, [4]. These new vertices can not be used further for the construction of the unitary corrections in the theory and they can be understood as the production vertices of real particles in the high energy scattering in the quasi-multi-Regge kinematics, for which the Lipatov’s action is defined, see [1, 2, 6,7,8,9] Some part of these vertices can be interpreted as impact factors of interactions of reggeon fields with the gluons or quark (antiquark) fields.

Formalism of Lipatov’s effective action

S-matrix for the gluon production amplitudes

S-matrix for the quark production amplitudes

Conclusion