Results on the hadronic final state in e/sup +/e/sup -/ annihilation at 13, 17 and 27.4 GeV are presented. There is no compelling evidence for the existence of the t quark in these data, which are in general agreement with a simple quark parton model. Some tentative indications of QCD effects are observed in the p/sub T//sup 2/ distributions.
TAU HEAVY LEPTON CONTRIBUTION SUBTRACTED.
INCLUSIVE HADRON SPECTRUM. THESE DATA AT 13, 17 AND 27.4 GEV ON S*D(SIG)/DX ARE INCLUDED IN THE RECORD OF R. BRANDELIK ET AL., PL 89B, 418 (1980).
We report on the results of the study of e + e − collisions at the highest PETRA energy of √ s = 31.57 GeV, using the 4π sr, electromagnetic and calorimetric detector Mark J. Based on 88 hadron events, and an integrated luminosity of 243 nb −1 we obtain R = σ (e + e − → hadrons)/ σ (e + e − → μ + μ − ) = 4.0 ± 0.5 (statistical) ± 6 (systematic). The R value, the measured thrust distribution and average spherocity show no evidence for the production of new quark flavors.
CORRECTIONS FOR TWO-PHOTON PROCESSES, TAU HEAVY LEPTON PRODUCTION AND INITIAL STATE RADIATIVE CORRECTIONS HAVE BEEN APPLIED.
THRUST DISTRIBUTION (1/N)*DN/DTHRUST AT 31.57 GEV. THESE DATA ARE RATHER DETECTOR DEPENDENT.
Backward production of ω (1670) is observed in the reactions K − p→ φ + φ − ω 0 Λ 0 and K − p→ φ + φ − φ 0 φ 0 for | U ' Λ |<1.0 GeV 2 . The cross section for the ω (1670) → φ + φ − ω 0 decay mode is 1.90±0.35 μ b for 8.25 GeV/ c incident K − . Evidence is presented for the importance of the sequential decay, ω (1670) → B φ → ωφφ with a branching ratio ω (1670) → B φ /all ω (1670) → ωφφ =1.0± 0.25 0.00 .
No description provided.
Two (Δ(1238)ππ) enhancements at 1.93 and 2.12 GeV have been observed in an analysis of the invariant-mass spectra of Δ++(1238)π-π0 and Δ++(1238)π-π- from π-p→π-pπ+π-π0 events in 4.5 GeV/c π-p interactions. An enhancement at 2.2 GeV is also seen with a dominant branching to the Δ(1238)ρ system. The 1.93 and 2.12 enhancements seem to be produced mainly through a ρ-meson exchange process. The 2.2 GeV enhancement seems to be produced diffractively and is considered to correspond to theG17(2190) state.
No description provided.
EXPONENTIAL FITS TO T-DISTRIBUTIONS.
This paper reports on the first results of the study of e+e− collisions at s=27.4 GeV and s=27.7 GeV at PETRA, using the 4π-sr electromagnetic and calorimetric detector MARK-J. We obtain an average R=σ(e+e−→hadrons)σ(e+e−→μ+μ−)=3.8±0.3 (statistical)±0.6 (systematic) and a relative R=1.0±0.2 between the two energies. The R values, the measured thrust distribution, and average spherocity show no evidence for the production of new quark flavors.
THE RELATIVE VALUE OF R BETWEEN THESE TWO ENERGIES IS 1.0 +- 0.2.
THRUST DISTRIBUTION (1/N)*DN/DTHRUST AT 13, 17 AND 27 GEV. THESE DATA ARE RATHER DETECTOR DEPENDENT.
Measurement was made of dσdt for n↑+p↑→n+p at P⊥2=0.8 and 1.0 (GeV/c)2 at 6 GeV/c. The 6-GeV/c 53%-polarized neutrons from the 12-GeV/c polarized deuteron beam at the Argonne zero-gradient synchroton were scattered from our 75%-polarized proton target. Both spins were oriented perpendicular to the scattering plane. We found large unexpected spin-spin effects in n−p elastic scattering which are quite different from the p−p spin-spin effects.
No description provided.
We have measured the polarization of the Λ hyperon produced in the reaction π−p→K0Λ at 3 and 5 GeV/c, for four-momentum transfers t′ out to 1.6 GeV2, by observing the parity-violating decay Λ→pπ−. With an increase in statistical power by a factor of 3 to 4 over the best previous experiments in this energy range, we confirm earlier observations that the polarization is small and positive below t′=0.4 GeV2, becoming large and positive for larger values of t′. In particular, at 5 GeV/c for all t′ between 0.8 and 1.6 GeV2 the polarization is consistent with a value of - 1.
No description provided.
No description provided.
The e + e − → p p cross section has been measured between 1925 and 2180 MeV. About 50 p p events were detected. The total cross section decreases from 1.31 ± 0.4 nb near 1937 MeV to 0.55 ± 0.2 nb near 2135 MeV. The proton form factors | G E | 2 and | G M | 2 , assumed identical, decrease from 0.15 ± 0.05 to 0.043 ± 0.015. They are an order of magnitude higher than predicted by the well-known dipole fit. The energy range has been scanned in steps of about 2 MeV. No significant structure was found in this p p sample.
TOTAL CROSS SECTION ASSUMING ISOTROPIC PRODUCTION. RADIATIVE CORRECTIONS CALCULATED USING PEAKING APPROXIMATION (ABOUT 20 PCT). AUTHORS ALSO QUOTE RESULTS FOR LIMITED (COSMIC RAY FREE) ACCEPTANCE AS A CHECK. FORM FACTOR DERIVED ASSUMING ELECTRIC AND MAGNETIC FORM FACTORS EQUAL IN MAGNITUDE.
Measurements have been made of the double polarisation parameters G and H in the photoproduction of neutral pions from protons, for incident photon energies between 1300 MeV and 2300 MeV and for pion c.m. angles between 50δ and 80δ. The results are compared with predictions from a recent comprehensive analysis of earlier photoproduction data.
No description provided.
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DATA OBTAINED IN ASSUMPTION THAT RHO(MM=00,P=3,XYZ=SH)=1-2*RHO(MM=1-1,P=3,XYZ=SH).
INTEGRATED CROSS SECTION, INCLUDING SYSTEMATIC UNCERTAINTY IN ERRORS Axis error includes +- 15/15 contribution (DECAY-BR(BRN=OMEGA --> PI0 GAMMA,BR=0.088 +- 0.005)).
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