Off-shell gluon production in interaction of a projectile with 2 or 3 targets

Within the effective QCD action for the Regge kinematics amplitudes for virtual gluon emission are studied in collision of a projectile with two and three targets. It is demonstrated that all un- Feynman singularities cancel between induced vertices and rescattering contributions. Formulas simplify considerably in a special gauge which is a straightforward generalization of the light-cone gauge for emission of real gluons.Comment: 13 pages, 6 figures; submitted to Eur.Phys.Jour.

On the application of the effective action approach to amplitudes with reggeon splitting

Application of the effective action approach to amplitudes with loop integration is studied for collisions on two and three centers with possible gluon emission. A rule is formulated for the integration around pole singularities in the induced vertices which brings the results in agreement with the QCD. It is demonstrated that the amplitudes can be restored from the purely transverse picture by introducing the standard Feynman propagators for intermediate gluons and quarks.Comment: 16 pages, 9 figures; submitted to Eur.Phys.Jour.

Gluon production on two centers and the effective action approach

Application of the effective action formalism is studied for processes in which the reggeons may split. It is shown that the gluon production on two centers is described by the contribution of the Reggeon-to-two-Reggeons-plus-Particle vertex supplemented by certain singular contributions from the double gluon exchange. The rules for longitudinal integrations are established from the comparison to perturbative QCD amplitude. Convenient expressions for application to the inclusive gluon production are derived.Comment: 15 pages, 7 figures; some misprints corrected; submitted to Eur.Phys.Jour.

Diffractive scattering on the deuteron projectile in the NLO: triple interaction of reggeized gluons

High-mass diffractive production of protons on the deuteron target is studied in the next-to-leading order (NLO) of the perturbative QCD in the BFKL approach. The non-trivial part of the NLO contributions coming from the triple interactions of the exchanged reggeons is considered. Analytic formulas are presented and shown to be infrared free and so ready for practical calculation.Comment: 28 pages, 2 figures; to be published in Eur.Phys.Jour.

Production of a gluon with the exchange of three reggeized gluons in the Lipatov effective action approach

In the Regge kinematics the amplitude for gluon production off three scattering centers is found in the Lipatov effective action technique. The vertex for gluon emission with the reggeon splitting in three reggeons is calculated and its transversality is demonstrated. It is shown that in the sum of all contributions terms containing principal value singularities are cancelled and substituted by the standard Feynman poles. These results may be used for calculation of the inclusive cross-section for gluon production on two nucleons in the nucleus.Comment: 22 pages, 9 figures; submitted to Eur.Phys.Jour.

Gluon emission in interaction of two reggeons

The vertex is constructed for gluon production in the interaction of two reggeons coupled to projectiles and two reggeons coupled to targets. The vertex can be used to build cross sections for collisions of two pairs of nucleons in AA scattering. The transversality of the constructed vertex is demonstrated as well as its good behaviour at large longitudinal momenta necessary for applications. Poles at zero values of longitudinal momenta are discussed and it is found that they remain in the amplitudes unlike in the case of a single projectile

Gluon production in the Lipatov effective action formalism

Gluon production on two scattering centers is studied in the formalism of reggeized gluons. Different contributions to the inclusive cross section are derived with the help of the Lipatov effective action. The AGK relations between these contributions are established. The inclusive cross section found is compared to the one in the dipole picture and demonstrated to be the same