Neutral kaon production ine+e−,ep,

Abstract

We present new sets of fragmentation functions for neutral kaons, both at leading and next-to-leading order. They are fitted to data on inclusive K 0 production in e + e − annihilation taken by MARK II at PEP ( √ s = 29 GeV) and by ALEPH at LEP. Our fragmentation functions lead to a good description of other e + e − data on inclusive K 0 production at various energies. They also nicely agree with the K 0 S transverse-momentum spectra measured by H1 at the DESY ep collider HERA, by UA5 at the CERN SppS Collider, and by CDF at the Fermilab Tevatron.

Fragmentation functions of mesons in the Field-Feynman model

“…In principle, the flavor structure of the kaon fragmentation functions is more complicated than that of the pion, as revealed by the FieldFeynman model. However, some available parametrizations [10][11][12][13] usually make only distinction between the favored fragmentation functions, which are related to the valence quarks of the kaon, and the unfavored fragmentation functions, which are related to the light-flavor sea quarks of the kaon. parameters used in this work can be also constrained by further detailed studies, or the framework should be extended to more general situation with more sophisticated aspects taken into account.…”

Photoproduction of $K^0$ and $\Lambda$ at HERA and a comparison with deep inelastic scattering

“…The authors of [6] calculate the inclusive single-particle photoproduction cross sections as follows. The hard subprocess is calculated to next-to-leading order in QCD, as is the evolution of the fragmentation and parton distribution functions.…”

“…Recent next-to-leading order QCD calculations of inclusive particle spectra in ep scattering use fragmentation functions which have been fitted to e + e − data [6]. These NLO calculations involve four scales: the factorization scales connected with the parton densities of the photon and the proton, the factorization scale of the fragmentation functions and the renormalization scale of the QCD coupling constant.…”

“…This arbitrariness in the choice of the scales introduces a change in the predicted cross sections and is a measure of the contribution of higher-order terms. To reduce the scale influence, the calculation for the photoproduction of neutral kaons was restricted to transverse K 0 momenta p t > 1 GeV, although the theoretical predictions should be more reliable for transverse momenta above 3 GeV [6]. A comparison of data with this calculation is shown in Fig.…”

“…The process dependence of particle production rates is studied by comparing the rates of strangeness production in γp and in pp. Finally, results from next-to-leading order (NLO) QCD calculations [6] and from Pythia [7,2] are compared with the measurements.…”