Quark-Antiquark-Gluon Jets in DIS Diffractive Dissociation

TL;DR

This work develops a perturbative QCD framework to study diffractive DIS events that produce hard quark–antiquark–gluon jets in the region of large diffractive masses (small β). It derives a comprehensive differential cross section for e p → e' q q̄ g p in forward kinematics using leading logs in 1/x_IP and 1/β while retaining all powers of k_T^2/Q^2, and reformulates the result in an impact-parameter/dipole picture with the unintegrated gluon distribution. A numerical study with RAPGAP in asymptotic and HERA-like kinematics shows that q q̄ g final states can contribute non-negligibly to the diffractive cross section and often produce three-jet topologies, especially at small β, informing the understanding of hard Pomeron dynamics. The analysis also discusses factorization aspects, links to a gluon component of the Pomeron structure function in soft limits, and stresses the potential of jet-based observables (thrust, angular correlations) to probe the hard-soft transition in diffractive QCD.

Abstract

We study the diffractive production of $q\bar{q}g$ jets with large transverse momenta in the region of large diffractive masses (small $β$). Cross sections for transverse and longitudinal photons are obtained in the leading log $1/x_{\fP}$ and log $1/β$ approximation, keeping all powers in log $k_t^2/Q^2$. We perform a numerical study and illustrate the angular distribution of the three jets. We also estimate the integrated diffractive three jet cross section and compare with the dijet cross section obtained before.

Figures (20)

• Figure 1: Dijet Production. The exchanged gluons couple to the quarks in all possible ways.
• Figure 2: Three jet Production. The exchanged gluons couple to the quarks in all possible ways.
• Figure 3: Notations for the diffractive production of a $q\bar{q}g$ system.
• Figure 4: Diagrams for the cross section of diffractive $q\bar{q}g$ production. We only show the diffractive system: at the lower end the two-gluon systems on both sides couple to the gluon structure function of the proton. At the upper end, the gluons couple to the quark loop in all possible ways. We do not show the vertical discontinuity line which divides each diagram into left and right hand pieces.
• Figure 5: Kinematic Boundaries. The drawn line belongs to $S=0$.