Scaled momentum distributions of charged particles in dijet photoproduction at HERA

TL;DR

This paper measures the scaled momentum distributions of charged particles in dijet photoproduction at HERA, comparing results to QCD predictions and extracting key parameters like Lambda_eff and kappa^ch.

Contribution

It provides the first detailed measurement of these distributions in dijet photoproduction and tests perturbative QCD predictions using MLLA and LPHD frameworks.

Findings

Measured distributions agree with QCD predictions within uncertainties

Extracted universal MLLA scale Lambda_eff and LPHD parameter kappa^ch

Confirmed the applicability of MLLA and LPHD in this context

Abstract

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb-1. The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, Lambda_eff, and the LPHD parameter, kappa^ch, are extracted.