Charged particles and neutral kaons in photoproduced jets at HERA

ZEUS Collaboration:     J. Breitweg et al.

EPJ

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2019 Impact factor 4.389

Particles and Fields

Eur. Phys. J. C 2, 77-93

Charged particles and neutral kaons in photoproduced jets at HERA

ZEUS Collaboration, J. Breitweg et al.

Argonne National Laboratory, Argonne, IL, USA

Received: 18 November 1997

Abstract
Charged particles ( $h^\pm$ ) and K⁰ mesons have been studied in photoproduced events containing at least one jet of E_T > 8GeV 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 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 K⁰ behaviour is possible with PYTHIA using a reduced value of the strangeness suppression parameter. The numbers of $h^\pm$ and K⁰ within a jet as defined above are measured to be $3.25\pm0.02\pm0.28$ and $0.431\pm0.013\pm0.088$ respectively. Fragmentation functions are presented for $h^\pm$ and K⁰ in photoproduced jets; agreement is found with calculations of Binnewies et al. and, at higher momenta, with $p\bar p$ 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.