Charged particles and neutral kaons in photoproduced jets at HERA

Abstract

Charged particles (h"#+-#) and K"0 mesons have been studied in photoproduced events containing at least one jet of E_T > 8 GeV in a pseudorapidity interval (-0.5, 0.5) in the ZEUS laboratory frame. Distributions are presented in terms of transverse momentum, pseudorapidity and distance of the particle from the axis of a jet. The properties of h"#+-# within the jet are described well using the standard settings of PYTHIA, but the use of the multiparton interaction option improves the description outside the jets. A reasonable overall description of the K"0 behaviour is possible with PYTHIA using a reduced value of the strangeness suppression parameter. The numbers of h"#+-# and K"0 within a jet as defined above are measured to be 3.25#+-#0.02#+-#0.28 and 0.431#+-#0.013#+-#0.088 respectively. Fragmentation functions are presented for h"#+-# and K"0 in photoproduced jets; agreement is found with calculations of Binnewies et al. and, at higher momenta, with pp scattering and with standard PYTHIA. Fragmentation functions in direct photoproduced events are extracted, and at higher momenta give good agreement with data from related processes in e"+e"- annihilation and deep inelastic ep scattering. (orig.)Available from TIB Hannover: RA 2999(97-229) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman