Measurement of the E(T,jet)^2/Q^2 dependence of forward-jet production at HERA

TL;DR

This paper measures the dependence of forward-jet production cross sections on E(T,jet)^2/Q^2 at HERA, testing perturbative QCD predictions and highlighting the importance of resolved photon contributions.

Contribution

It provides the first detailed measurement of E(T,jet)^2/Q^2 dependence in forward-jet production, comparing data with NLO pQCD and Monte Carlo models.

Findings

Models agree at low E(T,jet)^2/Q^2

Only models with resolved photon describe the full range

Data constrains QCD treatments of log(E_T/Q)^2 terms

Abstract

The forward-jet cross section in deep inelastic ep scattering has been measured using the ZEUS detector at HERA with an integrated luminosity of 6.36 pb^-1. The jet cross section is presented as a function of jet transverse energy squared, E(T,jet)^2, and Q^2 in the kinematic ranges 10^-2<E(T,jet)^2/Q^2<10^2 and 2.5 10^-4<x<8.0 10^-2. Since the perturbative QCD predictions for this cross section are sensitive to the treatment of the log(E_T/Q)^2 terms, this measurement provides an important test. The measured cross section is compared to the predictions of a next-to-leading order pQCD calculation as well as to various leading-order Monte Carlo models. Whereas the predictions of all models agree with the measured cross section in the region of small E(T,Jet)^2/Q^2, only one model, which includes a resolved photon component, describes the data over the whole kinematic range.