Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.
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We have measured the B hadron energy distribution in Z0 decays using a sample of semi-leptonic B decays recorded in the SLD experiment at SLAC. The energy of each tagged B hadron was reconstructed using information from the lepton and a partially reconstructed charm-decay vertex. We compared the scaled energy distribution with several models of heavy quark fragmentation. The average scaled energy of primary B hadrons was found to be <x_E_B> = 0.716 +- 0.011 (stat.) +0.022 -0.021 (syst.).
Bin center values for X are given.
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This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+ $ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.
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Integrated charm cross sections in two Q**2 regions.
Distribution of the fractional momentum of the D* in the gamma*-p system.
We present a study of the inclusive ω and η′ production based on 3.1 million hadronic Z decays recorded with the L3 detector at LEP during 1991–1994. The production rates per hadronic Z decay have been measured to be 1.17±0.17 ω mesons and 0.25±0.04 η′ mesons. The production rates and the differential cross sections have been compared with predictions of the JETSET and the HERWIG Monte Carlo models. We have observed that the differential cross sections can be described by an analytical quantum chromodynamics calculation.
Final production rates per hadronic Z0 decay.
Corrected production rates from the omega --> pi+ pi- p0 decay mode. Extrapolation to full x range.
Corrected production rates from the etaprime --> pi+ pi- eta decay mode. Extrapolation to full x range.
We present a study of the inclusive production of π 0 , η, K s 0 and Λ based on 929,000 hadronic Z decays recorded with the L3 detector at LEP. The measured inclusive momentum distributions have been compared with predictions from parton shower models as well as an analytical Quantum Chromodynamics calculation. Comparing to low energy e + e - data, we find that QCD describes the energy evolution of the hadron spectrum.
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We present a study of the inclusive η production based on 300 000 hadronic Z 0 decays. The measured inclusive momentum distribution can be reproduced by parton shower Monte Carlo programs and also by an analytical QCD calculation. Comparing our results with low energy e + e − data, we find that QCD describes both the shape and the energy evolution of the η spectrum. The comparison of η production rates in quark- and gluon-enriched jet samples does not show statistically significant evidence for more abundant production of η mesons in gluon fragmentation.
Differential cross section for inclusive eta production, normalized to the total hadronic cross section.
Differential cross section for inclusive eta production, normalized to the total hadronic cross section.
We present a study of the inclusive production of neutral pions and charged particles from 112 000 hadronic Z 0 decays. The measured inclusive momentum distributions can be reproduced by parton shower Monte Carlo programs and also by an analytical QCD calculation. Comparing our results to e + e − data between √ s = 9 and 91 GeV, we findfind that the evolution of the spectra with center of mass energy is consistent with the QCD predictions.
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Error is dominated by systematic uncertainties.
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Distributions of the Bjorken scaling variables x and y, and the structure function F+(x), are presented both for neutral-current and for charged-current νμ interactions. The data were obtained by use of the Fermilab 15-ft neon bubble chamber exposed to a narrow-band νμ beam. Results are based on 151 neutral-current and 683 charged-current events. An important feature of the neutral-current analysis is the event-by-event reconstruction of the outgoing neutrino.
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DATA REQUESTED FROM C.BALTAY ON 20/9/91.
DATA REQUESTED FROM C.BALTAY ON 20/9/91.
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