The production of N ∗ (1400) isobar in the reaction pp → pN ∗+ (1400), where N ∗ (1400) → n π + and p π 0 , is investigated with the aid of one-pion exchange model. The one-pion exchange mechanism does not seem to dominate the production process. The isospin of N ∗ (1400) is found to be I = 1 2 , and the elasticity of the resonance is estimated to be 0.66.
Axis error includes +- 0.0/0.0 contribution (?////Due to fitting mass spectrum).
The polarization parameter in elastic π−p scattering has been measured, at the Berkeley 184-in. synchrocyclotron, with the use of a polarized proton target. At 318-, 337-, and 390-MeV incident pion kinetic energy, the angular range from 70° to 180° in the center-of-mass system was covered. At 229 MeV, polarization measurements were made in the angular range 150° to 180°. Phase-shift analyses, using these and other published data, were made at the two lowest energies.
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The differential cross sections for single-π+ photoproduction from hydrogen have been measured over a range of momentum transfers from -2×10−4 to -2 (GeV/c)2, and photon energies from 5 to 16 GeV. The differential cross section increases by roughly a factor of 2 as the magnitude of the square of the momentum transfer decreases from 0.02 (GeV/c)2. The cross section falls approximately as exp(−3|t|) at large momentum transfers, with a similar momentum-transfer dependence of the cross section at all photon energies studied.
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The polarization parameter in proton-proton scattering has been measured at incident proton kinetic energies of 1.7, 2.85, 3.5, 4.0, 5.05, and 6.15 BeV and for four-momentum transfer squared between 0.1 and 1.0 (BeV/c)2. The experiment was done with an unpolarized proton beam from the Bevatron striking a polarized proton target. Both final-state protons were detected in coincidence and the asymmetry in counting rate for target protons polarized parallel and antiparallel to the scattering normal was measured. The maximum polarization was observed to decrease from 0.4 at 1.7 BeV to 0.2 at 6.1 BeV. The maximum of the polarization at all energies studied occurs at a four-momentum transfer squared of 0.3 to 0.4 (BeV/c)2.
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The elastic scattering of K+ mesons on protons is studied at 3.5 and 5 GeV/c. The total elastic cross-sections are found to be (4.36±0.36) mb and (3.82±0.41) mb respectively. The differential elastic cross-sections, which exhibit characteristic diffraction peaks, are fitted by dσ/dt=(dσ/dt)0eαt, giving α=(3.85±0.12) and (4.70±0.21) (GeV/c)−2 for the two momenta respectively, with |t|⪝0.65 (GeV/c)2. The results are compared to those at neighbouring energies, giving some support to the presence of a real part of the forward scattering amplitude. The diffraction peak shows definite shrinking with increasing momenta. The data are examined in the light of models for high-energy scattering.
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The importance of two-photon exchange in elastic electron-proton scattering was investigated by measuring the ratio of positron-proton to electron-proton scattering. Four-momentum transfers as large as 0.756 (BeV/c)2 (19.5 F−2) were used. The data indicate that two-photon effects are (4.0±1.5)% larger than those predicted by the radiative corrections at the highest momentum transfers attained in these experiments. The two-photon corrections predicted using a static charge distribution fit the data well at lower momentum transfers and forward angles, but appear to be small at higher momentum transfers and backward angles.
Data recalculated from the data of Yount and Pine.
Data recalculated from the data of Yount and Pine. RUN_1 and RUN_2 of the Yount and Pine experiment were separated by large time interval.
Data recalculated from the data of Yount and Pine.
The polarization of the recoil proton in neutral single-pion photoproduction from hydrogen, γ+p→p+π0, has been measured for pion center-of-mass angles near 90° at 7 photon energies from 450 to 900 MeV. The polarization rises to a maximum of 0.58 near 600 MeV and is still 0.42 at 900 MeV. The sign of the polarization is negative in the sense of k×q, where k is the photon momentum and q is the pion momentum. The measured values are given as functions of laboratory photon energy and c.m. pion angle as follows: 450 MeV, 109°, -0.16±0.14; 525 MeV, 84°, -0.36±0.19; 585 MeV, 86°, -0.58±0.15; 660 MeV, 77°, -0.51±0.17; 755 MeV, 76°, -0.55±0.15; 810 MeV, 89°, -0.45±0.17; 895 MeV, 90°, -0.42±0.16. The recoil protons were momentum-analyzed with a magnetic spectrometer. Nuclear emulsion was used as scatterer and detector. The emulsion technique is discussed in detail. The number of individual scatterings in emulsion used for each measurement varied between 750 and 1000.
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