Substructure of jets at HERA

TL;DR

This paper investigates the internal structure of jets produced in various interactions at HERA, comparing experimental data with theoretical models to understand quark and gluon jet differences and measure the strong coupling constant.

Contribution

It provides detailed measurements of jet substructure in different interaction types and compares them with Monte Carlo and QCD calculations, enhancing understanding of jet formation.

Findings

Good agreement between data and Monte Carlo models for jet substructure.

Extraction of gluon jet substructure from quark-induced samples.

Determination of alpha_s using NLO QCD calculations.

Abstract

The substructure of jets produced in an exclusive and a charm-induced dijet sample in photoproduction and in charged and neutral current interactions has been studied with the ZEUS detector at HERA. Jets were identified using the longitudinally invariant k_T cluster algorithm in the laboratory frame. The substructure of jets has been studied in terms of the jet shape and subjet multiplicity. Comparisons between the dijet sample and the quark-induced samples allow an extraction of the jet substructure for gluons. Leading-logarithm parton-shower Monte Carlo calculations give a good description of the differences between quark- and gluon-initiated jets. In neutral current interactions, the measurements have been compared to next-to-leading-order QCD calculations which are used to make a determination of the strong coupling constant, alpha_s.