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.