Inclusive Dijet Production at Low Bjorken-x in Deep Inelastic Scattering

TL;DR

This paper investigates inclusive dijet production at low Bjorken-x in deep inelastic scattering, comparing experimental data with various QCD models, highlighting where models succeed or fail, especially at small azimuthal jet separations.

Contribution

It provides a detailed comparison of experimental dijet cross sections with perturbative QCD calculations and alternative models at low x and Q^2, emphasizing the importance of CCFM evolution and other approaches.

Findings

NLO QCD describes most data well across phase space.

Significant discrepancies occur at small azimuthal jet separation.

CCFM evolution better models the small azimuth region.

Abstract

Dijet production in deep inelastic ep scattering is investigated in the region of low values of the Bjorken-variable x (10^-4 < x < 10^-2) and low photon virtualities Q^2 (5 < Q^2 < 100 GeV^2). The measured dijet cross sections are compared with perturbative QCD calculations in next-to-leading order. For most dijet variables studied, these calculations can provide a reasonable description of the data over the full phase space region covered, including the region of very low x. However, large discrepancies are observed for events with small separation in azimuth between the two highest transverse momentum jets. This region of phase space is described better by predictions based on the CCFM evolution equation, which incorporates k_t factorized unintegrated parton distributions. A reasonable description is also obtained using the Color Dipole Model or models incorporating virtual photon structure.