Gluon emission at small longitudinal momenta in the QCD effective action approach

Abstract

In the framework of the QCD effective action the vertices of gluon emission in interaction of reggeons are studied in the limit of small longitudinal momenta of the emitted gluon. It is found that the vertices drastically simplify in this limit so that the gluon becomes emitted from a single reggeon coupled to the projectile and target via multireggeon vertices. Contribution from this kinematical region is studied for double and 2×2 elementary collisions inside the composite projectile and target.

Lipatov's QCD high energy effective action: past and future

“…Similar to the previous example, the high energy limit of this correlator is captured by the corresponding diagram with an internal reggeized gluon exchange, such that the subtracted contribution, Fig. 5, second line, is local in rapidity in the sense that the expression vanishes up to terms O(1/(k − 1 ) 2 in the high energy limit [17], see also the discussion of a related observation in [18].…”

“…Among the results which we did not review here, are the effective action for Regge processes in gravity [41], earlier versions of an high energy effective action [5][6][7] as well as the determination of the 3 → 3 reggeized gluon transition kernel, needed for the NLO Bartels-Kwiecinski-Praszalowicz equation in [42] and the NLO corrections to the Mueller-Tang jet impact factor [43][44][45]. Another line of research has been developed in a series of papers [18,[46][47][48][49][50][51][52][53] dedicated to the study of production processes at central rapidities in the presence of multiple reggeized gluon exchange. The relation of the high energy effective action to the Color Glass Condensate approach as well as the further development of the underlying formulation has been explored in [54,55] and continued in [56][57][58][59][60].…”