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.
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This paper describes a measurement of the neutron-proton differential cross section made at the Argonne National Laboratory Zero Gradient Synchrotron. The differential cross sections, based on about 470 000 events, are presented for 8 different momentum ranges between 4.5 and 12.5 GeV/ c . The data extend from small angles out to about 145° in the c.m.s., corresponding to 0.14 < − t ⪅ 19 (GeV/ c ) 2 at the highest energies. These results in conjunction with previous np charge-exchange data provide almost complete angular distributions in this momentum range. A detailed comparison of the data with existing pp data and with theoretical predictions is made.
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Inclusive ϱ 0 production has been investigated in p p reactions at 22.4 GeV/ c . The total cross section for ϱ 0 production is 8.1 ± 2.0 mb. The average ϱ 0 's per event is 0.17 ± 0.03. The average transverse momentum, as obtained by extrapolation of a fitted simple exponential to the p T 2 distribution, is 0.52 ± 0.12 GeV/ c . The Feynman x and c.m. rapidity distributions show ϱ 0 to be “centrally” produced.
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The parameters D, R, R' and P for pp elastic scattering have been measured in the centre-of-mass angular range 13 degrees to 58 degrees with an accuracy of about +or-0.02 at 209, 324, 379, 425 and 515 MeV. These results are incorporated with earlier data into a phase-shift analysis. Phase-shifts are generally in agreement with the theoretical predictions of the Paris group, although the F-wave spin-orbit combination is rather stronger than predicted. The fitted value for the pi 0pp coupling constant in g02=14.06+or-0.65.
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Measurements are presented of the cross sections for omega meson photoproduction at a mean energy of 3.9 GeV from nuclear targets of D, Be, C, Al, Cu, Ag, Au. An optical and Glauber model analysis of the coherent cross sections has been performed to obtain the ω-nucleon cross section, σ ωN , and the photon-omega coupling constant γ ω 2 /4 π . Our results are summarised in table 4. We find good agreement with the quark model prediction that σ ω N = σ ϱ N , and with the value of γ ω 2 /4 π determined from the storage ring experiments and from an earlier complex nuclei measurement. However, we disagree with more recent complex nuclei measurements which found a high value of γ ω 2 /4 π .
COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.
COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.
In this paper we have investigated the properties of the D(1285) and E(1420) meson resonances using the five-body annihilation channels p p → K K πππ obtained in a large statistics experiment (28 events/μb). The analysis favours the 1 + spin-parity assignment for the D(1285) meson. The dominant decay mode of the D(1285) into K K π is found to be δ(970)π. The situation concerning the E(1420) meson remains confused although not inconsistent with previous analyses. Partial cross sections on resonance production are also presented.
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The mass spectrum of muon pairs in the range 5 to 15 GeV is studied in the inclusive reaction p+nucleus→μ++μ−+anything. The ϒ and continuum distribution are presented as is the A dependence of the continuum. Comparison with a parton-annihilation model yields a sea-quark distribution.
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Measurements of inclusive scattering in the target-fragmentation region are extended to higher incident energy. The combined data set shows departures from an approach to the asymptotic scaling limit as A+Bs−12 that are significant even at the highest energies. When these departures are taken into account, the data approach a limit that is consistent with equal cross sections induced by particles and antiparticles and with Pomeron factorization. The corrections to A+Bs−12 are so large that detailed tests of Mueller-Regge relationships are not conclusive.
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Inclusive single-particle spectra for π± production are presented for data from π±p interactions at 100 GeV/c. The spectra for the four reactions π±p→π±+anything are compared as a function of laboratory longitudinal momentum, Feynman x, center-of-mass (c.m.) rapidity, and transverse momentum squared. Comparisons are also made between these data and analogous data from 16 and 18.5 GeV/c π±p interactions and the energy dependence is discussed. Average values of the transverse momentum are given as a function of the longitudinal momentum and charged-particle multiplicity. A comparison of the charge distributions is presented as a function of rapidity and c.m. energy.
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We have measured the ratio of inclusive production of η to π0 at transverse momenta above 1.5 GeV/c. Results are presented for various meson and proton beams with momenta of 100, 200, and 300 GeV/c incident upon a hydrogen target. The ηπ0 production ratio is found to be independent of incident beam momentum and of the transverse and longitudinal momenta of production. The ratio for pion- and proton-induced reactions is 0.44 ± 0.05; for kaons, it is 0.74 ± 0.12.
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