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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We report measurements of semi-inclusive pion electroproduction from both hydrogen and deuterium targets carried out at the Wilson Synchrotron Laboratory at Cornell University. Measurements were made at the (W, Q2) points (2.15 GeV, 1.2 GeV2), (2.15, 4.0), and (3.11, 1.2) with hydrogen and deuterium, and at (2.15, 2.0), (2.67, 3.3), and (3.11, 1.7) with hydrogen only. The invariant virtual-photoproduction cross section for pions scaled by the total cross section is studied as a function of x′, pT2, W, and Q2. The invariant structure function shows no Q2 dependence and a weak W dependence. The ratio of π+ to π− production is also presented, but a distinction between a universal ω or W dependence cannot be made.
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We report measurements of the electroproduction of single charged pions from hydrogen and deuterium targets for values of ε in the range 0.35<ε<0.45. Data were taken with a hydrogen target at the (W, Q2) points (2.15 GeV, 1.2 GeV2), (2.65, 2.0), (2.65, 3.4), (2.65, 6.0), and (2.65, 10.0). Data were taken with a deuterium target at the (W, Q2) points (2.15, 1.2) and (2.65, 2.0). The transverse cross section obtained by using these data in conjunction with earlier data at high ε to separate the longitudinal and transverse components is used in conjunction with the new data and the t-channel Born term to determine the pion form factor and to re-evaluate previously reported measurements. In the range 0.15 GeV2<Q2<10.0 GeV2 the pion form factor can be described by the simple pole form [1+Q2(0.462±0.024)]−1.
SEPARATED TRANSVERSE AND LONGITUDINAL VIRTUAL-PHOTON CROSS SECTIONS PREVIOUSLY PUBLISHED IN C. J. BEBEK ET AL., PRL 37, 1326 (1976).
DATA POINT 1 (HYDROGEN TARGET).
DATA POINT 1 (HYDROGEN TARGET).
This paper reports measurements of the inclusive pion electroproduction reaction e+N→e+π±+ anything with both proton and neutron targets for pions produced along and near the direction of the virtual photon. Two independent purposes of these measurements were to provide data at low ε and at high Q2. Data are reported for the (W,Q2,ε) points (2.2 GeV, 1.2 GeV2, 0.45), (2.7, 2.0, 0.35), (2.7, 3.3, 0.40), (2.7, 6.2, 0.40), and (2.7, 9.5, 0.40). The data are used to test Feynman scaling and to compare the ratio of the cross sections for charged-pion production to the quark-model predictions. The data are also used in conjunction with the data from earlier experiments to separate the scalar and transverse components of the cross section.
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We present evidence for a large scalar contribution to the cross section for the reaction ep→eK+Λ. No evidence for a scalar contribution is found for the reaction ep→eK+Σ0. This is reminiscent of the results for the π+n and π+Δ0 final states.
AVERAGED OVER PHI. FOR LOW EPSILON, SOME DEUTERIUM DATA ARE INCLUDED. INCLUDING EARLIER MEASUREMENTS AT HIGH EPSILON.
AVERAGED OVER PHI. INCLUDING EARLIER MEASUREMENTS AT HIGHER EPSILON.
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POLARIZATION PARAMETER P(N000).
POLARIZATION PARAMETER A(00N0).
WOLFENSTEIN PARAMETER D(N0N0).
Measurements have been made of the target asymmetry parameter for photoproduction of π 0 mesons from protons, using a butanol polarised target with a 3 He cryostat. Results were obtained at 14 incident photon energies between 0.7 GeV and 1.45 GeV over an angular range ∼40° to 145° c.m. The recent analysis of Barbour and Crawford provides a very good fit to the data.
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We report measurements of kaon electroproduction from hydrogen and deuterium targets carried out at the Wilson Synchrotron Laboratory at Cornell University. The reactions γVp→K+X0, K+Γ, and K+Σ0 were studied in the kinematic region 2.15≤W≤3.1 GeV and 1.2<Q2<4.0 GeV2 as a function of Q2, W, and ω. The K+Σ0 cross sections fall much more rapidly with increasing Q2 than the K+Λ cross sections so that K+Σ0KΛ→0 as Q2 increases.
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FIRST 11 DATA POINTS ARE FROM THE PRESENT EXPERIMENT. THE NEXT 4 DATA POINTS ARE HARVARD-CORNELL DATA: BEBEK ET AL., PRL 32, 21 (1974). THE LAST 8 DATA POINTS ARE CEA DATA: BROWN ET AL., PRL 28, 1086 (1972).
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We report measurements of the exclusive electroproduction reaction e+p→e+π++n for pions produced near 0° in the virtual-photon-proton center-of-mass system with values of ε in the range 0.35<ε<0.45. Combination with data taken at ε near 1 allows us to separate the contributions from transversely polarized and scalar photons in the range 1.2 GeV2<Q2<3.3 GeV2.
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Measurements of the polarised beam asymmetry parameter Σ for eta photoproduction from protons, have been carried out at incident energies of 2.5 GeV and 3.0 GeV, and for various t -values between −0.2 (GeV/c) 2 and −1.2 (GeV/c) 2 . The values of Σ are close to +1 for values of | t | less than 0.7 (GeV/c) 2 , showing that there can be little contribution from unnatural parity exchange in any Regge exchange model of the process, in disagreement with present theories. Differential cross sections for the process werre also measured, and are consistent with those from other experiments.
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