Absolute measurements of the elastic electron-proton cross section have been made with a precision of about 4% for values of the square of the four-momentum transfer, q2, in the range 6.0 to 30.0 F−2 and for electron scattering angles in the range 45° to 145°. To within the experimental errors, it is found that the charge and magnetic form factors of the proton have a common dependence on q2 when normalized to unity at q2=0, and that an accurate representation of the behavior of the form factor and that of the cross sections themselves can be given in terms of a three-pole approximation to the dispersion theory of nucleon form factors.
Axis error includes +- 2./2. contribution (RANDOM ERROR).
Axis error includes +- 2./2. contribution (RANDOM ERROR).
Axis error includes +- 2./2. contribution (RANDOM ERROR).
Elastic electron-proton scattering cross sections were measured at backward angles (80°-90°) in the laboratory for four-momentum transfers between 7 F−2 and 45 F−2. Experimental errors range from 3.1% to 5.3%, including a systematic error estimated to be 1.9% added in quadrature. Electric and magnetic form factors are computed from all the recent data in this q2 range, with allowance made for possible normalization differences. The results show a deviation from the scaling law.
No description provided.
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Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
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Reactions p p → p p and p p → n n were studied at the kinetic energy 230 MeV of incident p by using bubble chamber films. Total cross sections for both of the reactions were found to be 51.2 ± 1.6 mb and 9.1 ± 0.6 mb, respectively. Differential cross sections are well explained by the phenomenological theory given by Bryan and Phillips.
No description provided.
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In a study of the production mechanism of quasi-two-body final states at the five incident π+ momenta 2.95, 3.2, 3.5, 3.75, and 4.08 GeV/c, approximately 40 000 events with four outgoing charged particles were investigated. The cross sections for the processes π+p→N*++ρ, π+p→N*++ω, π+p→N*++η, and π+p→N*++f have been measured as a function of the pion energy. The differential cross sections and the decay density-matrix elements are discussed in terms of one-meson-exchange models [with absorption (OPEA) and with form factor (OPEW)] and Regge models. For the N*++ρ and the N*++ω reactions, the joint-decay matrix elements are calculated. The formation of N*(2850) in the direct channel is also investigated.
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Lambda production is studied in K − p interactions at 10.1 GeV/ c , where the dominant reaction is K − p → Λ + pions. General characteristics such as the distributions of the double differential cross section in the lab system, of the variable x = p L ∗ p max ∗ , of p ⊥ 2 and of the missing mass to the lambda are presented. Total cross sections for Λ production and for the various channels are given. Differential cross sections d σ d t , d σ d t′ and d σ d u′ are presented. Forward and backward peaks are observed in the d σ d t′ and d σ d u′ distributions, respectively. It is found that the exponential slope of these distributions decreases with increasing missing mass to the lambda and, for d σ d t′ , also for increasing multiplicity in the final state. The polarization of the lambdas is studied as a function of multiplicity, p L ∗ , (Λπ ± ) effective mass, t ′ and u ′. The forward lambdas show
No description provided.
POSSIBLE FORWARD DIP.
The reaction K − d → K − π + π − n p s was studied in a bubble chamber experiment. The cross section was measured to be 1.3 ± 0.2 mb. The final state is dominated by K ∗0 (890) , K ∗0 (1420) and Δ − (1236) production. Partial cross sections, differential cross sections and decay angular distributions of the K ∗0 (890) δ − (1236) final state were found to give good agreement with the predictions of Białas and Zalewski obtained from the quark model. The final state K − π + Δ − (1236) is analyzed by use of the Van Hove plot.
DEUTERIUM CROSS SECTIONS WITH SPECTATOR PROTON. PROBABLY NOT CORRECTED FOR K* BRANCHING RATIO INTO <K- PI+>.
SLOPE IS 5.75 +- 0.46 GEV**2 FOR -TP < 0.4 GEV**2.
GOTTFRIED-JACKSON FRAME.
We have measured the total inelastic cross section (σinel) and charged-particle multiplicities obtained in pp collisions at 405 GeV/c. The data are from a preliminary 12 000-picture bubble-chamber exposure. We find σinel=32.8±1.0 mb; the low moments of the multiplicity distribution for negative particles are 〈n−〉=3.50±0.07, D−=2.37±0.05, f2−=2.1±0.2, and f3−=0.1±0.9. We also present updated results at 102 GeV/c.
SUPERCEDES PRELIMINARY RESULTS IN J. W. CHAPMAN ET AL., PRL 29, 1686 (1972).
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FIT TO ELASTIC DIFFERENTIAL CROSS SECTION FOR 0.05 < -T < 0.7 GEV**2.
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APPROXIMATELY CONSTANT MOMENTUM TRANSFER.
The single diffraction dissociation process pp → (p π + π − )p has been studied at the CERN ISR at √ s = 45 GeV and 0.1 < − t < 0.6 GeV 2 . The reaction is dominated by nucleon resonance production: pp → pN (1520) and pp → pN(1688) with cross-sections (0.25 ± 0.08) mb and (0.56 ± 0.19) mb respectively.
DIFFERENTIAL CROSS SECTIONS FOR THREE RANGES OF <P PI+ PI-> MASS.
FROM BREIT-WIGNER PLUS BACKGROUND FITS. CORRECTIONS FOR OTHER DECAY MODES USE THE PDG 1974 TABLES FOR N(1520) AND N(1688).
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