Photon-Reggeon Interaction Vertices in the Nla

TL;DR

This work computes the photon–Reggeon interaction vertices in the next-to-leading approximation, focusing on virtual photon–Reggeized gluon collisions that produce a quark–antiquark pair or a quark–antiquark–gluon state. Starting from Born-level vertices, the authors derive the one-loop corrections by analyzing two-gluon and one-gluon exchange diagrams, and they present both integral representations and helicity-based forms. The resulting vertices, including ultraviolet-renormalized and infrared-cancelled pieces, provide essential ingredients for the virtual photon impact factor at NLA and have broader applicability to diffractive processes involving Reggeized gluons. The work corroborates Reggeization properties and offers detailed methodologies for handling complex loop diagrams within the BFKL framework.

Abstract

We calculate the effective vertices for the quark-antiquark and the quark-antiquark-gluon production in the virtual photon - Reggeized gluon interaction. The last vertex is considered at the Born level; for the first one the one-loop corrections are obtained. These vertices have a number of applications; in particular, they are necessary for calculation of the virtual photon impact factor in the next-to-leading logarithmic approximation.

Figures (8)

• Figure 1: The lowest order Feynman diagrams for the process $\gamma^* Q \rightarrow (q\bar{q})Q$.
• Figure 2: Schematic representation of the vertex $\Gamma^{c(0)}_{\gamma^*q\bar{q}}$.
• Figure 3: The quark-quark-Reggeon and the gluon-gluon-Reggeon effective vertices. $T^c$ is the colour group generator in the adjoint representation.
• Figure 4: Schematic representation of the vertex $\Gamma^{c(0)}_{\gamma^*q\bar{q}g}$.
• Figure 5: The two-gluon exchange Feynman diagrams for the process $\gamma^*Q \rightarrow (q\bar{q})Q$.