A high-statistics measurement of the reaction π − p→ η n; η →2 γ has been performed at the 70 GeV Serpukhov accelerator for 15, 20, 25, 30 and 40 GeV/ c incident pion momentum using the NICE set-up with its associated 648-channel hodoscope spectrometer for γ-ray detection. It is found that the spin-flip and non-spin-flip amplitudes can be parametrized, for small | t |, as exponentials with the same slopes to within a few percent. For | t | ≳ 1 (GeV/ c ) 2 there is a break in the differential cross section. In addition, the A 2 effective trajectory deviates markedly for | t | ≳ 1 GeV/ c ) 2 from the linear behaviour valid for smaller | t |.
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The production of the ϒ family in proton-nucleus collisions is clarified by a sixfold increase in statistics. Constraining ϒ,ϒ′ masses to those observed at DORIS we find the statistical significance of the ϒ′′ to be 11 standard deviations. The dependence of ϒ production on pt, y, and s is presented. Limits for other resonance production in the mass range 4-18 GeV are determined.
Cross section times branching ratio.
No description provided.
We report the first measurement of the ratio R=(σe+e−→hadrons)(σe+e−→μ+μ−) (with negligible τ-lepton contribution) at a center-of-mass energy s=13 GeV and s=17 GeV, from the just finished electron-positron colliding-beam facility PETRA. The detector, MARK-J, has an approximately 4π solid angle and measures γ, e, μ, and charged and neutral hadrons simultaneously. Our results yield R(s=17 GeV)=4.9±0.6 (statistical) ±0.7 (systematic error), and R(s=13 GeV)=4.6±0.5 (statistical) ±0.7 (systematic error). The ratio R(s=17 GeV)R(s=13 GeV) is 1.08±0.18.
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We have measured the differential cross-section and the analyzing power (polarization) for p-He4 elastic scattering at incident kinetic energies of 0.56, 0.80, 1.03, 1.24, and 1.73 GeV. The experiment used a polarized proton beam incident on a liquid helium target and a single arm magnetic spectrometer to detect elastic scattering. Both the differential cross sections and the analyzing power show structure near −t=0.25 (GeV/c)2 which decreases in magnitude with increasing energy. Both multiple scattering and optical model interpretations of the data are discussed. NUCLEAR REACTIONS elastic scattering, p-He4; GeV energies; measured differential cross section; measured polarization; comparison with theory.
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On a selected sample of 2171 events, observed in the big heavy liquid bubble chamber Gargamelle at CERN, the charged current total cross section for antineutrino on nucleons has been determined up to the laboratory energy E v ̄ = 8 GeV . The total cross section is found to be a linear function of the antineutrino energy expressed by σ tot (E v ̄ ) = (0.26 ± 0.020) × 10 −38 × E v ̄ ( GeV ) cm 2 . The energy dependence of 〈q 2 〉 v ̄ is found to be given by 〈q 2 〉 v ̄ = (0.15 ± 0.04)E v ̄ + (0.05 ± 0.12) ( GeV /c) 2 . With a simplified nuclear model the ratio of cross sections on neutrons andprotons has been estimated as a function of energy and for two different values of the scaling variable x . The results are compared with the prediction of the naive quark parton model.
Measured charged current total cross section.
The inclusive production of Ξ − and Ξ ∗0 (1530) is investigated in K − p interactions at 10 and 16 GeV/ c . The inclusive production cross sections are 172 ± 20 μ b and 135 ± 15 μ b for the Ξ − , and 43 ± 7 μ b and 32 ± 5 μ b for the Ξ ∗0 (1530) at 10 and 16 GeV /c , respectively. In the beam momentum range up to 16 GeV/ c , the energy dependence of the cross section for Ξ − production in K − p interactions is similar to Σ − production in π − p interactions. It is, instead, different from the energy behaviour of Σ − production cross sections observed in π − p interactions. The Ξ − and Ξ ∗0 (1530) are both produced more in the forward ( x > 0) than in the backward hemisphere, indicating the presence of hyperon-exchange processes.
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The energy dependence of the K L 0 -K S 0 transmission regeneration amplitudes on deuterons and neutrons in the momentum region 10–50 GeV/ c is determined. The moduli of the modified transmission amplitudes are momentum dependent. These dependences are fitted by the expression A j p − nj , where A j and n j ( j = d, n) are constants: A d =2.88 ±0.04 mb , n d =0.546±0.030, for deuterons , A n =1.97 ±0.14 mb , n n =0.530±0.019, for neutrons , The amplitude phases do not depend on the kaon momentum and are equal to ϕ d = (−130.9 ± 2.7)° ϕ n = (−132.3 ± 1.7)°. The mean value of the ratio of the total cross-section differences for K 0 and K 0 interactions with neutrons and protons is determined. The residues of the partial ω and ϱ amplitudes, which contribute to the kaon-nucleon interaction amplitudes, are also obtained.
FORWARD CROSS SECTION, AMPLITUDE AND PHASE FOR K0 REGENERATION.
(AK0 - K0) TOTAL CROSS SECTION DIFFERENCES.
Cross-section values or upper limits are presented for twenty-five two-body hypercharge-exchange reactions in K − p and π + p interactions at 10 and 16 GeV/ c . The 16 GeV/ c results are compared with some predictions of line-reversal plus exchange-degenerate Regge poles, of SU(3) and of the additive quark model. Agreement is found in all cases.
No description provided.
A sample of 56 909 events of the reaction π − p→K + K − n at 10 GeV/ c has been measured in the Omega Spectrometer at CERN. In the K + K − system, besides production of mesons in the S ∗ /φ, f 0 / A 2 , g /ω ∗ and h regions we observe a new structure at 2.20 GeV with a width of the order of 200 MeV.
BREIT-WIGNER RESONANCES PLUS SMOOTH BACKGROUND FITTED TO K+ K- MASS SPECTRUM. RESTRICTIVE T-CUTS TO ENHANCE THE X(2200) GIVE CONSISTENT RESULTS.
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.
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