We report on a high statistics study of π0 and η production in continuum events and in direct decays of the Γ(1S) and Γ(2S) resonances. The measured production rates per event are\(\left\langle {n_{\pi ^0 } } \right\rangle\)=3.22 ± 0.07 ± 0.31 (3.97 ± 0.23 ± 0.38) and 〈nη〉=0.19 ± 0.04 ± 0.04 (0.40 ± 0.14 ± 0.09) for continuum events (direct Γ(1S) decays).
First data point in table is from the continuum at sqrt(s)=9.46 GeV.
First data point in table is from the continuum at sqrt(s)=9.46 GeV.
PI0 spectrum in the continuum.
Using the ARGUS detector at thee+e− storage ring DORIS II, we have investigated inclusive production of π±,K±,Ks0 and\(\bar p\) in multihadron events at 9.98 GeV and in direct decays of the ϒ(1S) meson, i.e. from quark and gluon fragmentation. The most pronounced difference is the rate of baryon production. The Lund Monte Carlo program gives a reasonable qualitative description, although it cannot reproduce our data in detail.
No description provided.
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No description provided.
We report the first observation of an orbitally excited baryon, the Λ(1520), in quark and gluon fragmentation. The production rate is found to be (1.15±0.21±0.16)×10 −2 and (0.80±0.17 −0.13 +0.10 )×10 −2 Λ (1520) hyperons per event in direct ϒ decays and in the continuum, respectively. In contrast to the observed situation for ground state baryons, the production of the Λ(1520) in direct ϒ decays shows little or no enhancement with respect to continuum production.
Full X range uses extrapolation from fit to dsig/dz distribution.
No description provided.
UPSI(1S) DECAYS.
We report on a high precision measurement of ϕ-meson production in continuum events and in direct decays of the Υ(1S)- and Υ(2S)-mesons. The ratio of the total production rate of ϕ-mesons in direct Υ(1S)- and Υ(2S)-decays over that in continuum events is 1.32±0.08±0.09 and 1.07±0.13±0.11 respectively. This is compatible with the corresponding ratio obtained for lighter mesons, but is appreciably smaller than the relative baryon production rate.
PHI meson cross section on the continuum.
Differential particle density for PHI mesons in decays of upsilon(1S) and upsilon(2S).
No description provided.
η production has been investigated by the Mark II collaboration at the SLAC e+e− storage ring PEP. η particles are reconstructed by their γγ decay mode. The η fragmentation function has been measured and found to be in good agreement with the Lund-model prediction. η′ production has been measured for the first time in high-energy e+e− annihilation. There is evidence at the 3σ level for Ds± decay into ηπ± and η′π±.
Numerical values supplied by G.Wormser.
Z = 0.0 point extrapolated using LUND fragmentation model.
Z = 0.0 point extrapolated using LUND fragmentation model.
The production cross sections for the Λ, Σ0, Ξ−, Σ0 (1385), Ξ0 (1530) and Ω− hyperons have been measured, both in the continuum and in direct ϒ decays. Baryon rates in direct ϒ decays are enhanced by a factor of 2.5 or more compared to the continuum. Such a large baryon enhancement cannot be explained by standard fragmentation models. The strangeness suppression for baryons and mesons turns out to be the same. A strong suppression of spin 3/2 states is observed.
Hyperon rates per multihadronic event in direct UPSILON decays.
Hyperon rates per multihadronic event in the continuum.
LAMBDA spectrum (1/SIG(had))*D(SIG)/D(X) for UPSILON (1S) direct decays, with X = P/Pmax.
Inclusive distributions of ρ0 and ω mesons have been measured in deep inelastic μ-p interactions at 280 GeV/c. A comparison of the ρ0 cross sections with other leptoproduction experiments is presented. The ω results represent the first observation of this inclusive channel in high energy leptoproduction. The ρ0 and ω yields are found to be equal as may be expected from the available density of states in isospin space. This contrasts with spin angular momentum where the vector to pseudoscalar meson ratio is suppressed relative to the available number of spin states.
No description provided.
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This paper presents measurements of the inclusive production cross sections of Λ baryons in e+e− annihilations at s=29 GeV. The data sample corresponds to an integrated luminosity of 256 pb−1 collected with the High-Resolution Spectrometer at the SLAC storage ring PEP. Comparisons are made to the predictions of the Lund model. The data are well described with use of a strange-diquark suppression parameter, (usud)(sd), of 0.89 ± 0.10−0.16+0.56, and the measured Λc→Λ+X branching ratio of (23 ± 10)%.
No description provided.
Rapidity relative to thrust axis.
Corrected for unobserved moment regions.
Inclusive production of charged particles has been studied in e + e − annihilation at s s=29 GeV using the high resolution spectrometer at PEP. Differential cross sections are presented in the range of scaled energy 0.1< z <1.0. The data for z <0.5 show the (1− z ) 2 behavior predicted by the dimensional counting rules. Comparisons are made with predictions of the Lund string model and the Webber cluster model.
Data requested from authors.
The production of charmed D* mesons in e+e− annihilations at a center-of-mass energy of 29 GeV has been studied using the time-projection-chamber (TPC) detector at the SLAC storage ring PEP. The production cross section, fragmentation function, and forward-backward asymmetry due to electroweak effects are measured, and a limit on D0-D¯0 mixing is determined.
No description provided.
No description provided.
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