Inelastic electron proton scattering has been measured by detecting the scattered electron, thus obtaining the total absorption cross section for virtual photons. Two complete spectra from threshold to a pion nucleon mass of W = 2 GeV were taken at θ e = 48.3° and fixed primary energies of 3.963 GeV and 5.159 GeV, respectively, corresponding to a momentum transfer at the first resonance of q 2 = 3.98 (GeV/ c ) 2 and q 2 = 5.84 (GeV/ c ) 2 . In addition, a measurement at θ e = 47.9° and at a primary energy of 3.306 GeV in the region of the first resonance is reported.
No description provided.
Electron-proton elastic scattering cross sections have been measured at the Stanford Linear Accelerator Center at four-momentum transfers squared (q 2 ) of 1.0, 1.5, 2.0, 2.5and 3.75 (GeV/ c ) 2 . The angular distributions at q 2 = 2.5 and 3.75 (GeV/ c ) 2 are sufficient to provide values of the ratio G E / G M independent of the results from other laboratories. Our results are compatible with scaling, G E (q 2 ) = G M (q 2 )/ μ , within the experimental errors.
No description provided.
No description provided.
No description provided.
Electron-proton elastic scattering cross sections have been measured at squared four-momentum transfers q 2 of 0.67, 1.00, 1.17, 1.50, 1.75, 2.33 and 3.00 (GeV/ c ) 2 and Electron scattering angles θ e between 10° and 20° and at about 86° in the laboratory. The proton electromagnetic form factors G E p and G M p were determined. The results indicate that G E p ( q 2 ) decreases faster with increasing q 2 than G M p ( q 2 ). Quasi-elastic electron-deuteron cross sections have been determined at values of q 2 = 0.39, 0.565, 0.78, 1.0 and 1.5 (GeV/ c ) 2 and scattering angles between 10° and 12°. At q 2 = 0.565 (GeV/ c 2 data have also been taken with θ e = 35° and at q 2 = 1.0 and 1.5 (GeV/ c ) 2 with θ e = 86°. Electron-proton as well as electron-neutron scattering cross sections have been deduced by the ratio method. The theoretical uncertainties of this procedure are shown to be small by comparison of the bound with the free proton cross sections. The magnetic form factor of the neutron G M n derived from the data is consistent with the scaling law. The charge form factor of the neutron is found to be small.
Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).
Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).
Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).
We have studied photoproduction using a 1 m streamer chamber at DESY and a tagged photon beam with an energy range of 1.6 GeV < E γ < 6.3 GeV. We analysed approximately 30 000 events and report topological, channel and resonance production cross sections for a large number of reactions with three and five outgoing charged particles.
CHANNEL CROSS SECTIONS FOR 3, 5 AND 7 PRONG REACTIONS.
'PARAMETRIZATION'.
'INTERFERENCE'.
Qausi-elastic ω production by ep scattering in the kinematic region 0.3. < Q 2 < 1.4 GeV 2 and 1.7 < W < 2.8 GeV was studied using a streamer chamber at DESY. The production angular distribution for γ V p → ω p has a strong non-peripheral component for W < 2 GeV. The ω production cross section falls by a factor of 4 as W changes from 1.7 to 2.8 GeV. In contrast the cross section for ω production with | t | < 0.5 GeV 2 is W independent between 1.7 and 2.8 GeV and for W > 2.0 GeV consistent in both W and Q 2 dependence with the predictions of a model based on one-pion exchange and diffraction.
FOR ALL T-VALUES. THE GAMMA* P TOTAL CROSS SECTION WAS TAKEN FROM A FIT TO THE DATA OF S. STEIN ET AL., PR D12, 1884 (1975). 'PPD'.
'PPD'. PERIPHERAL OMEGA PRODUCTION.
No description provided.
None
THE DATA POINTS AT -T = 0.40 AND 0.60 GEV**2 WERE OBTAINED FROM THE PAPER BY J. P. DE BRION ET AL., NP B32, 557 (1971). THESE DATA OF O. GUISAN ET AL., PL 18, 200 (1965) ARE USED TO DETERMINE THE ABSOLUTE NORMALIZATION.
Cross sections for ρ0 electroproduction measured in a streamer-chamber experiment are separated into elastic (ep→epρ0) and inelastic production channels. For the elastic channel, the total cross section and t dependence are presented. For the inelastic channel (1σ)dσdz, (1σ)dσdpT2, and a density matrix element are shown and compared to quark-parton-model predictions. The ratio of ρ0 to direct π0 production is found to be 2.0±0.5±0.3, where the first error is statistical, and the second error is systematic.
No description provided.
No description provided.
No description provided.
We have used the momentum spectrum of leptons produced in semileptonic B-meson decays to set a 90%-confidence-level upper limit on Γ(b→ulν)Γ(b→clν) of 4%. We also measure the semileptonic branching fractions of the B meson to be (12.0±0.7±0.5)% for electrons and (10.8±0.6±1.0)% for muons.
No description provided.
No description provided.
The proton elastic electric and magnetic form factors, GEp(Q2) and GMp(Q2), have been separately measured in the range Q2=1.75 to 8.83 (GeV/c)2, more than doubling the Q2 range of previous data. Scaled by the dipole fit, GD(Q2), the results for GMp(Q2)/μpGD(Q2) decrease smoothly from 1.05 to 0.91, while GEp(Q2)/GD(Q2) is consistent with unity. Comparisons are made to QCD sum rule, diquark, constitutent quark, and vector meson dominance models, none of which agree with all of the new data. The ratio Q2F2/F1 approaches a constant value for Q2>3 (GeV/c)2.
Magnetic form factors.
Electric form factors.
Quasielastic e-d cross sections have been measured at forward and backward angles. Rosenbluth separations were done to obtain RL and RT at Q2=1.75, 2.50, 3.25, and 4.00 (GeV/c)2. The neutron form factors GEn and GMn have been extracted using a nonrelativistic model. The sensitivity to deuteron wave function, relativistic corrections, and models of the inelastic background are reported. The results for GMn are consistent with the dipole form, while GEn is consistent with zero. Comparisons are made to theoretical models based on vector meson dominance, perturbative QCD, and QCD sum rules, as well as constituent quarks.
Magnetic form factors.
Electric form factors.
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