Measurement of Internal Jet Structure in Dijet Production in Deep-Inelastic Scattering at HERA

TL;DR

This paper measures the internal structure of jets produced in deep-inelastic scattering at HERA, analyzing jet shapes and subjet multiplicities to understand QCD dynamics.

Contribution

It provides detailed measurements of jet substructure in deep-inelastic scattering, comparing results with QCD models to test their accuracy.

Findings

Jets become more collimated with higher transverse energy.

Jet shape and subjet multiplicity depend on jet energy and pseudorapidity.

QCD models describe the data reasonably well.

Abstract

Internal jet structure in dijet production in deep-inelastic scattering is measured with the H1 detector at HERA. Jets with transverse energies ET,Breit > 5 GeV are selected in the Breit frame employing k_perp and cone jet algorithms. In the kinematic region of squared momentum transfers 10 < Q2 <~ 120 GeV2 and x-Bjorken values 2.10^-4 <~ xBj <~ 8.10^-3, jet shapes and subjet multiplicities are measured as a function of a resolution parameter. Distributions of both observables are corrected for detector effects and presented as functions of the transverse jet energy and jet pseudo-rapidity. Dependences of the jet shape and the average number of subjets on the transverse energy and the pseudo-rapidity of the jet are observed. With increasing transverse jet energies and decreasing pseudo-rapidities, i.e.towards the photon hemisphere, the jets are more collimated. QCD models give a fair description of the data.