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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Measurements of the cross section for the production of electron pairs with invariant masses between 4 and 8.7 GeV are presented as a function of the centre-of-mass energy ( s = 28 to s = 62 GeV ) of the colliding proton beams. A significant excess of events is observed in the region 8.7 to 10.3 GeV; these are ascribed to the ϒ(9.5 GeV) resonances and estimates of the production cross sections are given.
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
The inclusive production of resonances is systematically studied in K + p interactions at 32 GeV/ c . Total production cross sections are given for three baryon resonances, five vector and three 2 + tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.
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Quasi-inclusive and total inclusive ϱ + , ϱ − and ϱ 0 cross sections have been studied, using data of a π + p and a pp bubble chamber experiment at 16 and 24 GeV/ c , respectively. In pp collisions it is found that the total inclusive cross sections for ϱ 0 , ϱ + and ϱ − production are about equal. This equality also holds for the differential cross sections d σ/ d y ∗ , all showing the characteristics of dominantly central production. In the π + p reactions the ϱ − are mainly produced centrally, whereas there are strong additional contributions in the beam fragmentation region for ϱ + and ϱ 0 mesons. In the central region, however, the cross sections for ϱ + , ϱ − and ϱ 0 production are almost equal within errors. All our findings agree with what is expected from quark model predictions.
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We have measured the inclusive electroproduction of positive and negative hadrons in the quark fragmentation region using the streamer chamber at DESY. Data are presented in terms of the variable z p = p / v in the kinematic region 1.8 < W < 2.8 GeV and 0.3 < Q 2 < 1.4 GeV 2 . The positive hadron distributions contain a strong proton component. After subtraction of the proton component and elastic rho events, the distribution (1/ σ tot ) d σ /d z p for positive and negative hadrons agrees well with the corresponding distribution from e + e − annihilation (DORIS data). This behaviour supports the validity of the quark-parton model at surprisingly low Q 2 and W .
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Measurements of inclusive cross sections at 100 GeV/c are presented for the double-charge-exchange reactions a+p→π−X with a=π, K, or p. The measurements covered a kinematic range in the Feynman x variable of 0.3<~x<~0.9 at transverse momenta of 0.3 and 0.5 GeV/c. A model summing the contributions from resonance production and from inclusive central-region π− production is used to fit the data and demonstrates the importance of resonance production via one-pion exchange for large values of the Feynman x.
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We report results from a measurement of the inclusive processes pp→Xp and pd→Xd in the range 5<Mx2s<0.1, 0.01≲|t|≲0.1 (GeV/c)2, and incident proton momenta of 65, 154, and 372 GeV/c. Both pp and pd data show an exponential t dependence and a dominant 1Mx2 behavior for Mx2s≲0.05. By comparing pp and pd data we test factorization and, using the Glauber model, we measure the XN total cross section, σXN=43±10 mb.
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We have measured the polarization parameter in π − p→K + Σ − backward scattering at 3.5 GeV/ c incident momentum, in the u -range −0.6< u <0.1 GeV 2 . The apparatus consisted of a polarized target in a spectrometer magnet, counter hodoscopes for time-of-flight measurements, a large water Čerenkov counter for kaon tagging, and wire spark chambers. After identification of the kaons, the reaction was selected by a missing-mass technique. An isospin analysis has been carried out to separate the contributions of the various isospin exchange amplitudes in the u -channel.
No description provided.
As a part of the study of the inclusive production of electron pairs in pp collisions at the CERN Intersecting Storage Rings (ISR), a search has been performed for additional photons accompanying J/ψ particles. The results suggest that (43±21)% of the J/ψ's are produced via the photonic decay of one of the χ(3.5) states.
The cross section times branching ratio.
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