The Process γ^{*}_L+ q \to q\bar{q}g + q: Real Corrections to the Virtual Photon Impact Factor

TL;DR

The paper addresses the real-emission contributions to the NLO virtual photon impact factor in high-energy γ*–hadron scattering by computing γ*+q→(qqbar g)+q in the Regge limit with a large rapidity gap. It provides explicit helicity-summed matrix elements organized into a detailed AA, AB, and BB interference structure and shows how these results can be recast into a photon-wave-function framework, introducing a qqbar g Fock component. A central-region subtraction scheme and careful consideration of energy-scale choices are developed to avoid double counting with LO BFKL and to ensure RG consistency, including DIS-limit checks. Together, these results advance the kt-factorization approach to NLO by laying groundwork for combining real and virtual corrections and for extending the photon-wave-function picture to higher Fock states and jet cross sections.

Abstract

We calculate, for the longitudinally polarized virtual photon, the cross section of the process γ^{*}+q\to (q\bar{q}g)+q at high energies with a large rapidity gap between the fragmentation system q\bar{q}g and the other quark. This process provides the real corrections of the virtual photon impact factor in the next-to leading order. Evidence is given for the appearance of a new q\bar{q}g Fock-component of the photon state.

Figures (4)

• Figure 1: Different contributions to the $\gamma^*$ impact factor at NLO.
• Figure 2: Kinematics of the process $\gamma^* + q \to q\bar{q}g + q$.
• Figure 3: Feynman diagrams for the process $\gamma^* + q \to q\bar{q}g + q$.
• Figure 4: Emission of a gluon from the lower quark line.