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No description provided.
We present the results obtained with the magnetic detector DM1 at the Orsay storage ring ACO for the reaction e + e − → π + π − π 0 from 483 to 1100 MeV in the center of mass. Our data show without ambiguity an interference effect between the ω and φ mesons, which corresponds to a negative coupling constant product ratio Re( g γω g ω →3 π / g γφ g φ →3 π ) ; however our measurements above the φ, performed using kinematical analysis, can only be explained by a higher energy contribution. In addition, the parameters of the ω have been obtained with an improved accuracy compared to other experiments, and particularly the branching ratio B ω →e + e − = (6.75±0.69) × 10 −5 . We confirm that the reaction e + e − → π + π − π 0 proceeds essentially via a quasi-two-body state ϱπ , at the energy of the φ.
FITTED CROSS SECTION AT OMEGA PEAK IS 1410 +- 130 NB AND AT PHI PEAK IS 615 +- 55 NB.
This paper summarizes the measurements one+e− annihilation performed by the DASP Collaboration in the energy range between 3.1 and 5.2 GeV. The following topics are covered: total cross section, production and two body decays of the narrow resonances, radiative decays of theJ/ψ and ψ′ resonances and evidence for theX(2.82), ψ′ cascade decays, inclusive η production and evidence for theF meson, semileptonic decays of charmed mesons and properties of the heavy lepton.
THESE DATA ON R WERE PUBLISHED IN R. BRANDELIK ET AL., PL 76B, 361 (1978), THE RECORD OF WHICH HAS TABULATED CROSS SECTIONS WITH AND WITHOUT THE TAU HEAVY LEPTON CONTRIBUTION.
OBSERVATION OF J/PSI RESONANCE.
OBSERVATION OF PSI(3700)0 RESONANCE.
We present the results of a measurement of the cross section oof the reaction e + e − → π + π − π + π − from 890 to 1100 MeV in the center of mass, obtained with a magnetic detector at the Orsay Storage Ring ACO. With respect to previous experiments, the present one offers the possibility of reconstructing events with at least one constraint and his improved statistics. We find that our measurement of the cross section for e + e − → π + π − π + π − is compatible with quasi two-body production of π A 1 ( m A1 = 1.1 GeV, Γ A1 ∼ 0.2−0.3 GeV), through the ϱ and ϱ′(1600) intermediate states. We were able to states. We were able to determine the cross section of this reaction at the energy of the φ meson and consequently an upper limit on the branching ratio of φ → π + π − π + π − .
UPPER LIMIT FOR PHI --> 4PI.
Inclusive cross sections of η production by e + e - annihilation for c.m. energies between 4.0 and 5.0 GeV are presented. The η production is shown to be correlated with the production of a weakly decaying particle, indicating that its main source is F production. At the 4.42 GeV resonance it is correlated with a low energy photon, suggesting F F ∗ or F ∗ F ∗ production. A mass determination of the F is made at 4.42 GeV using the F → ηπ decay channel.
NUMERICAL VALUES MEASURED FROM GRAPH IN PREPRINT. A CHARM MODEL (METHOD 2) GAVE CONSISTENT RESULTS FOR BACKGROUND SEPARATION.
Inclusive production of ifπ ± , K ± and p has been studied near charm threshold for c.m. energies between 3.6 and 5.2 GeV. Differential and scaling cross sections together with particle multiplicities have been determinated. By comparing data below and above charm threshold the charm contribution to if π ± and K ± production has been extracted. A comparison has been made between inclusice p production and inelastic electron-proton scattering. To study differences between three-gluon annihilation and two-quark production of the spectra from J/ decay and from non-resonant production at 3.6 GeV has been compared.
No description provided.
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Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e + e − annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e + e − → D or D + anything) at 7 GeV is 4.8±1.3 nb.
No description provided.
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SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
We have measured inclusive γ and π0 production in multiprong events produced by e+e− annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find the π0 inclusive cross section to be consistent in shape and normalization with half the charged-π cross section between x=0.15 and 0.60, with an integrated inclusive cross-section ratio of σ(π0)|σ(π+)+σ(π−)|=0.47±0.10.
NUMERICAL VALUES OF DATA FROM THIS EXPERIMENT HAVE NOT BEEN KEPT (M. L. PERL, PRIV COMM, 3 MAY 1979).
We have measured inclusive electron production in multiprong events produced by e+e− annihilation in the center-of-mass energy range 3.9-7.4 GeV. We find the electron momentum spectra are consistent with the electrons coming mainly from decays of charmed particles, with a smaller contribution from decays of the τ lepton. From our data we calculate the average branching ratio for charmed particles to decay into an electron plus additional particles to be (8.2±1.9)%.
No description provided.
The total cross section for e + e − annihilation into hadronic final states between 3.6 and 5.2 GeV was measured by the nonmagnetic inner detector of DASP, which has similar trigger and detection efficiencies for photons and charged particles. The measured difference in R = σ had / σμμ between 3.6 GeV and 5.2 GeV is ΔR = 2.1 ± 0.3. We observe three peaks at cm energies of 4.04, 4.16 and 4.417 GeV, the parameters of which, when interpreted as resonances, are given.
EXCLUDING CONTRIBUTION OF TAU HEAVY LEPTON.
INCLUDING CONTRIBUTION OF TAU HEAVY LEPTON.
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