Measurement of the Azimuthal Correlation between the most Forward Jet and the Scattered Positron in Deep-Inelastic Scattering at HERA

TL;DR

This paper measures the azimuthal correlation between forward jets and scattered positrons in deep-inelastic scattering at HERA, testing QCD evolution models through differential cross sections and distributions.

Contribution

It provides new measurements of azimuthal correlations in deep-inelastic scattering, comparing data to various QCD models and calculations.

Findings

Data shows sensitivity to different QCD evolution mechanisms.

Differential cross sections match some models better than others.

Results help refine understanding of QCD dynamics in forward jet production.

Abstract

Deep-inelastic positron-proton scattering events at low photon virtuality Q^2 with a forward jet, produced at small angles with respect to the proton beam, are measured with the H1 detector at HERA. A subsample of events with an additional jet in the central region is also studied. For both samples differential cross sections and normalised distributions are measured as a function of the azimuthal angle difference, Delta phi, between the forward jet and the scattered positron. The sensitivity to QCD evolution mechanisms is tested by comparing the data to predictions of Monte Carlo generators based on different evolution approaches as well as to next-to-leading order calculations.