Di-jet Event Rates in Deep-Inelastic Scattering at HERA

TL;DR

This paper measures di-jet event rates in deep-inelastic scattering at HERA, comparing data with various theoretical models, and finds that models including resolved photons or the colour dipole approach best match the observations.

Contribution

It provides the first detailed measurement of di-jet rates in this kinematic range and tests different QCD models against the data.

Findings

Models with resolved photons fit the data well.

Leading order point-like photon models fail to describe the data.

Next-to-leading order calculations agree with observations.

Abstract

Di-jet event rates have been measured for deep-inelastic scattering in the kinematic domain ~5 < Q^2 < ~100 GeV^2 and ~10^(-4) < x_Bj < ~10^(-2), and for jet transverse momenta squared p_t^2 > ~Q^2. The analysis is based on data collected with the H1 detector at HERA in 1994 corresponding to an integrated luminosity of about 2 pb^(-1). Jets are defined using a cone algorithm in the photon-proton centre of mass system requiring jet transverse momenta of at least 5 GeV. The di-jet event rates are shown as a function of Q^2 and x_Bj. Leading order models of point-like interacting photons fail to describe the data. Models which add resolved interacting photons or which implement the colour dipole model give a good description of the di-jet event rate. This is also the case for next-to-leading order calculations including contributions from direct and resolved photons.