The reaction e + e − → ω o has been measured by detecting the charged pions of the π + π − π o decay mode of the ω o. A partial decay width of ω o in e + e − : Γ e + e − =0.94±0.18 keV is deduced from this result.
FITTED, BACKGROUND SUBTRACTED, PEAK OMEGA CROSS SECTION, CORRECTED FOR UNOBSERVED DECAYS, IS 1.82 +- 0.34 MUB. TABULATED ASSUMING CENTRAL ENERGY IS 782.6 MEV. VACUUM POLARIZATION AND RADIATIVE CORRECTIONS APPLIED.
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The reaction e+d→e′+n+p was studied at electron scattering angles θ ⩽ 35° for four-momentum transfers of 0.39, 0.565 and 0.78 (GeV/ c ) 2 . By recording electron-neutron and electron-proton coincidences, the ratio of the electron scattering cross sections on quasi-free neutrons and protons was determined. An estimate of the binding effects, based on a Chew-Low-extrapolation, was made. Values for the neutron form factors were derived.
Axis error includes +- 0.0/0.0 contribution (Due to the different effective solid angles for neutron and proton detection in the counters).
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The cross section for inelastic electron-proton scattering was measured at incident electron energies of 1.5 to 6 GeV by magnetic analysis of the scattered electrons at angles between 10° and 35°. For invariant masses of the hardonic final state W ⩽ 1.4 GeV. the measured spectra are compared with theoretical predictions for electroproduction of the Δ(1236) isobar. The magnetic dipole transition form factor G ∗ M ( q 2 ) of the (γ N Δ)-vertex is derived for momentum transfers q 2 = 0.2 − 2.34 (GeV/ c ) 2 ard found to decrease more rapidly with q 2 than the proton form factors.
Axis error includes +- 0.0/0.0 contribution.
The transmission regeneration amplitude after a thick copper block has been measured. The quantity {∣ƒ(0)- overlineƒ(0)∣ }/{k} varies from 20.0 $\pm$ 1.4 mb at 2.75 GeV/c to 13.6 $\pm$ 1.2 mb at 7.25 GeV/c. Results are in agreement with optical model calculations in which real and imaginary parts of the amplitudes for single nucleon scattering are determined from forward dispersion relations and total cross-sections.
Regeneration amplitude.
Cross sections for the photoproduction of neutral pions have been measured at the 1.1-GeV Frascati electron synchrotron for bombarding photon energies k between 400 and 800 MeV and for π0 c.m. angles of θπ*=90∘, 120∘, and 135∘. The main feature of the experiment is good resolution in incident photon energy. The results are in good agreement with the existing theories in the energy range of 450 to 550 MeV. The cross sections exhibit a smooth behavior as a function of energy for k=400−600 MeV. No immediate evidence is found of a contribution of the P11 resonance. An anomaly at the limit of statistical significance appears for k≃700−740 MeV, indicating a possible structure of the so-called second resonance. We attempt to interpret the observed anomaly as a reflection of the sharp opening of the η production channel (η cusp effect).
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The cross section for the reaction [...] was measured at the Caltech synchrotron. The [...] was detected by measuring its decay gamma rays with two lead glass, total absorption Cherenkov counters. The results are three angular distributions at k = 911, 1180, and 1390 MeV, at forward angles from 3 degrees to 90 degrees. The deuteron/proton ratio differs significantly from 2.0, but final state effects from the use of a deuteron target make impossible quantitative conclusions about the neutron cross section.
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A bubble-chamber experiment in which the reaction π−+p→π+π+N was studied at a beam momentum of 2.14 BeV/c yielded 1533 and 2234 events of the final states π−π0p and π−π+n, respectively. These events are dominated by the formation of the ρ resonance, which is produced mostly in the forward direction. Both the production and decay angular distributions of the ρ− agree very well with the predictions of the one-pion exchange theory modified by absorption effects. The decay angular distribution of the ρ0 shows the well-known forward-backward asymmetry. This effect is interpretable as the result of the interference between the ρ0 and an isospin-zero s-wave π−π resonance. The production of the ρ0, in addition to its forward peak, shows a weak backward peak. Partial cross sections of various final states are also presented.
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NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Measurements have been made of the cross-sections for neutral meson photoproduction from protons at angles in the forward hemisphere for photon energies near 911, 1182, and 1390 MeV. The experimental method consists of detecting the decay gamma-rays of the neutral meson in two pb-glass total absorption Cerenkov counters. The results agree very well with the existing data where the same points have been measured. The striking feature of the angular distributions at 1182 and 1390 MeV is the small 0[degree] cross-section and the peak near 30[degrees] to 40[degrees] in the CMS. Using as a model for the cross-section calculation a vector meson X[degrees] exchange plus background, we find the product [...] for M[subscript X] = 788 MeV. Fits made without the vector meson pole are not inconsistent with a resonance model for the cross-section.
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