The differential cross section for the reaction e + e − → γγ has been measured in the CMS energy range between 9.4 and 31.6 GeV. The results are found to be in agreement with the predictions of quantum electrodynamics up to momentum transfers- q 2 of 900 GeV 2 . The data set lower limits of about 40 GeV on QED cut-off parameters. We have searched for the decay υ (9.46) → γγ and obtain an upper limit Γ ( υ → γγ )/ Γ ( υ → all) < 1.4% (95% c.l.).
None
We have measured the production cross section for K s 0 in e + e − annihilation from 3.6 to 5.0 GeV center of mass energy. A substantial increase of the K s 0 yield is observed around 4 GeV in qualitative agreement with the charm hypothesis.
THE DATA GIVEN HERE AT 9.3 GEV AND ABOVE ARE REPORTED IN C. BERGER ET AL., PL 104B, 79 (1981). THE 12.0 AND 30 GEV DATA WERE TAKEN AT PETRA.
No description provided.
No description provided.
We report on inclusive production of J ψ (3.1)-mesons observed in e + e − -annihilation in the energy range s = 4.0–5.0 GeV . After substraction of the radiative tail of the ψ(3.7) direct production of the J ψ (3.1) is found to be in the order of 0.1% of the total hadronic cross section. No enhancements are seen at s = 4.03 GeV and 4.4 GeV. The level is in agreement with expectations from violation of the Zweig-rule.
THIS IS 0.13 PCT OF THE TOTAL HADRONIC CROSS SECTION.
We present the first data on photon-photon annihilation into hadrons for CM energies > 1 GeV obtained with the detector PLUTO at the e + e − storage ring PETRA. Cross sections are extracted using an inelastic eγ scattering formalism. The results are compared to expectations from Regge-like models.
DEPENDENCE OF CROSS SECTION FOR ELECTRON-PHOTON SCATTERING (ANALOGOUS TO HAND'S FORMULA) ON VISIBLE HADRONIC ENERGY, CALCULATED BY TAKING PION MASSES FOR ALL CHARGED PARTICLES.
A multi-jet analysis of hadronic final states from e + e − annihilation in the energy range 27 < E cm < 32GeV is presented. The analysis uses a cluster method to identify the jets in a hadronic event. The distribution of the number of jets per event is compared with several models. From the number of identified coplanar three-jet events the strong coupling constant is determined to beα S = 0.15 ± 0.03 (stat. error) ± 0.02 (syst. error). The inferred energy distribution of the most energetic parton is in good agreement with the first-order QCD prediction. A scalar-gluon model is strongly disfavoured. Higher-twist contributions to the three-jet sample are found to be small.
No description provided.
Measurements of the charged multiplicities for hadron production in e + e − annihilation in the center of mass energy range 9–32 GeV have been made. The average charged multiplicity has an energy dependence much stronger than ln s and similar to that reported for pp collisions. Quantitative differences are observed in the magnitude of both the average multiplicity 〈 n ch 〉 and the dispersion D ch for e + e − and pp interactions at the same center of mass energy. 〈 n ch 〉 and the ratio 〈 n ch / D ch in e + e − annihilations are significantly larger than in pp collisions and are found to be in overall agreement with QCD predictions. KNO scaling is seen to be satisfied.
THE FINAL TABLE ENTRY COMBINES THE DATA FROM THE THREE HIGHEST ENERGY BINS.
First results from the magnetic detector PLUTO at the new e + e − storage ring PETRA are shown. The ratio R of the cross section for hadron production to that for μ-pair production has been measured to be R = 5.0 ± 0.5 at 13 GeV and 4.3 ±0.5 at 17 GeV. Both values have an additional systematic error of 20%. The events show a typical 2-jet structure. The mean transverse momentum approaches a constant value with increasing energy implying a shrinkage of the jet opening angle.
TAU HEAVY LEPTON PAIR CONTRIBUTIONS HAVE BEEN SUBTRACTED. R AT 13 AND 17 GEV, TOGETHER WITH SOME SELECTED LOWER ENERGY MEASUREMENTS FROM PLUTO AT DORIS.
Data from earlier preprint DESY-79-06. NUMERICAL VALUES MEASURED OFF GRAPH IN PREPRINT.
Annihilation of e + e − into final states with a single electron has been studied with the PLUTO detector at the DORIS storage ring at CMS energies from 3.6 to 5 GeV. In the sample of 4-prong events without any detected photon we observe 21 events which we assign to the reaction e + e − → τ + τ − → νν e + νϱ 0 π . We obtain a branching ratio for τ + → νϱ 0 π + of 0.050 ± 0.015 with an overall systematic uncertainty of 30%. The data are consistent with the ϱπ coming from an A 1 meson.
No description provided.
We have performed a search for narrow resonances in the center of mass energy range from 29.90 to 31.46 GeV using the e + e − storage ring PETRA at DESY. We present the total cross section for hadron production and an upper limit for resonance production, indicating that no bound state of charge- 2 3 quarks exists in this energy range.
AVERAGE VALUE OF R OVER THE SCAN REGION.
THESE MEASUREMENTS COMBINED WITH PREVIOUS DATA AT 30.0 AND 31.6 GEV REPORTED IN CH. BERGER ET AL., PL 86B, 413 (1979).
Forum