In the reaction p p → 3π + 3π − 2227 events, and in the reaction p p → 3π + 3π − π 0 6578 events have been analyzed. The general characteristics of the reactions, such as total cross sections, angular and momentum distributions, the production of ϱ, f, ω and η mesons, and angular correlations are presented.
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THETA being the angle between PI+ and P (or PI- and PBAR) in CMS.
THETA being the angle between PI+ and P (or PI- and PBAR) in CMS.
Absolute cross sections for Compton scattering from protons have been determined at 180° for the backscattered photon at incident laboratory photon energies of 98 and 132 MeV. For the difference between the electric and the magnetic polarizability of the proton a value of (7.03 − 2.37 +2.49 − 2.05 +2.14 ) × 10 −4 fm 3 has been derived using the predictions from calculations based on relativistic dispersion relations.
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The total cross section of the pp→ pp η reaction has been measured at incident proton energies of 1.265, 1.3, 1.4 and 1.5 GeV by detecting the two photons from the η decay in the PINOT spectrometer. The data are compared with other near-threshold measurements and with the predictions of existing theoretical calculations.
Value given at 1263 MeV assumes energy 2 MeV lower than nominal value. This uncertainty only affects this lowest energy point.
The doubly-differential cross sections for the pp → ppη and pd → ηX reactions have been measured at incident proton energies of 1.3 and 1.5 GeV. The ratio of the pd to pp -induced cross sections varies from about 8–10 at 1.3 GeV to 4.5–6 at 1.5 GeV in the η kinetic energy interval 100 MeV ⩽ T η ⩽220 MeV. Information on the pn → ηX reaction has been extracted from these measurements within the framework of a simple folding model.
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We present results on Λc+ production in 29-GeV e+e− annihilation. The Λc+ are observed via their semileptonic decays to Λe+X and Λμ+X. With radiative corrections, we find σ(e+e−→Λc+X)〉BΛc+→eΛX)= 1.5±0.6±0.5 pb or 0.0038±0.0015±0.0012 Λc+→Λe+X decay per hadronic event, and σ(e+e−Λc+X)B(Λc+→μΛX)= 1.4±1.4±0.4 pb or 0.0035±0.0035±0.0011 Λc+→Λμ+X decay per hadronic event. These results can be used to place constraints on the predictions of various production models.
Cross sections * branching ratio for LAMBDA/C+ production in LAMBDA E+ decay channel.
Cross sections * branching ratio for LAMBDA/C+ production in LAMBDA MU+ decay channel.
We report the result of a brief experiment to measure the cross section for photoproduction of Jψ(3100). At a mean energy of 55 GeV we find this cross section per nucleon to be 37.5 ± 8.2 (statistical) ± 4 (systematic) nb. The result establishes the previously indicated rise in Jψ photoproduction on protons above 20 GeV and suggests that the rise has occurred by 55 GeV.
CROSS SECTION PER NUCLEON DERIVED FROM DEUTERIUM DATA ASSUMING INCOHERENT PART OF T DISTRIBUTION HAS EXPERIMENTAL SLOPE OF 1.8 +- 0.4 GEV**-2, 6 PCT COHERENT PART CALCULATED WITH KNOWN DEUTERIUM WAVE FUNCTION AND NEGLECTING SHADOWING. The mean P quoted in the table assumes the J/PSI energy equals the photon energy.
Elastic ω-meson photoproduction on protons has been measured from 46 to 180 GeV. The cross section is approximately constant with photon energy and averages 1.10 ± 0.08 μb. The t dependence of the differential cross section is consistent with A exp(bt), where b=8.4±0.7 GeV−2. The photon-omega coupling constant, obtained from a normalization of hadron elastic-scattering cross sections to the photoproduction data of this experiment (with use of vector-meson dominance and an additive quark model), is γω24π=5.4±0.4.
THE QUOTED STATISTICAL ERRORS INCLUDE THE UNCERTAINTY IN THE CORRECTION FOR INELASTIC EVENTS. AVERAGE CROSS SECTION IS 1.10 +- 0.08 MUB.
EXPONENTIAL FIT TO DIFFERENTIAL CROSS SECTION.
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We present evidence for the existence of two strange J P = 1 − mesons; one at 1410 MeV/c 2 coupling principally to K ∗ (892)π , and the other at 1790 MeV/c 2 couplingto K π , K ∗ π and ϱ K. The data derive from a partial wave analysis of the K 0 π + π − system produced in the reaction K − p → K 0 π + π − n at 11 GeV /c . The production mechanism and quark model assignment of each state are discussed. The state at 1410 MeV/c 2 most naturally understood as the first radial excitation of the K ∗ (892), and the 1790 MeV/c 2 object can be interpreted as the triplet D wave partner to the 3 − K ∗ (1780).
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Differential cross sections for center of mass scattering angles near 90° are presented for the reactions K ̄ ° p → π + Λ° , K ̄ ° p → π + Σ° and K L °p → K S °p in the momentum interval 1.0 to 7.5 GeV / c . The energy dependences of these cross sections are found to be equally well described by the parameterization: ( d σ d Ω ) 90° ∞ s −2 or ( d σ d Ω ) 90° ∞ exp (− bp ⊥ ) .
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