Differential cross sections and polarizations have been measured for the reaction π − p → K 0 Λ and π − p → K 0 Σ 0 at 3.9 GeV/ c π − momentum. Comparison of these data with those of the related reactions K − n → π − Λ and K − p → π − Σ + (at approximately the same c.m. energy) indicate that simple Regge-pole models involving only K ∗ (890) and K ∗ (1420) exchange are unable to describe all the features of the data. On the other hand, comparison of the π − p → K 0 Σ 0 data with that of π + p → K + Σ + shows that the data are consistent with absence of exotic strange-meson exchange.
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The t -dependence of the differential cross-section for elastic neutron-proton charge exchange scattering has been measured at 8, 19.2 and 24 GeV/ c . The extremely narrow peak in the forward direction, previously observed for momenta up to 8 GeV/ c , presists at the higher momenta, and the t -dependence shows practically no change with energy. Approximate values of the absolute cross-section were also determined for these momenta.
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Proton Compton scattering has been measured in a coincidence experiment at photon energies between 2.2 and 7 GeV and four-momentum transfers t between −0.06 and −0.85(GeV/ c ) 2 . For ∣ t ∣ ⩽ 0.4 (GeV/ c ) 2 fits of the form d σ /d t = ( A · exp( Bt )) yield forward cross sections A in good agreement with the values calculated from the total hadronic γ p cross section via the optical theorem and the forward dispersion relation. The slopes B do not show a significant energy dependence, the mean value being 5.7 ± 0.4 (GeV/ c ) −2 . The cross section is substantially larger than predicted by the vector-meson dominance model.
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Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.
FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.
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NO TMIN CORRECTION HAS BEEN MADE.
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.
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Results are presented on effective-mass distributions, differentisl cross sections and longitudinal c.m. momentum distributions for the channels K − p → K − p π o , K o p π − and K − π + n , obtained from a sample of approximately 28 000 inelastic two-pronged interactions at 4.2 GeV/ c incident momentum. The results are in satisfactory agreement with the prediction of a generalized Veneziano-model corrected for (non-dual) π -and pomeron exchange. For the channel K − pπ o pomeron exchange contributes about 20% of the cross section. In the channel K − π + n the dual, pion and pomeron contributions are responsible for resp. 15%, 65% and 20% of the total cross section.
BREIT-WIGNER FITS.
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We present complete results concerning the five reactions K − p → Λω , K − p → Λφ , K − p → Σ 0 ϱ and K − p → Σ 0 φ . The experimental data are well described by exchange mechanisms and the agreement with the SU(3) symmetry predictions is excellent.
FORWARD AND BACKWARD CROSS SECTIONS ARE FOR COS(THETA) > AND < 0. SLOPE DETERMINED FOR -TP = 0.2 TO 1.0.
AUTHORS ALSO GIVE CORRELATIONS OF LAMBDA POLARIZATION WITH THE MESON POLARIZATION.
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Final states π − Σ + , π + Σ − , π o Λ and ηΛ were studied for K − p reactions at 3.95 GeV/ c . Cross sections, angular distributions and polarizations are presented. Data for π − Σ + and π o Λ production are compared to the line-reversed πp reactions at the same beam momentum. Baryon-exchange peaks are presented for the Σ + π − , Σ − π + and Λπ o final states.
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We present results of an analysis of two-prong events for elastic scattering and single-pion production in K−p interactions at 5.5 GeVc. The resonance parameters for the charged and neutral K*(890) and K*(1420) are determined and the observed production and decay properties of the charged and neutral K*(890) are compared with the theoretical predictions of an absorptive one-particle-exchange model and a Regge model. The K*(1420) differential cross section and density-matrix elements are presented and the question of whether more than one resonance exists in this mass range is considered. A search for resonance effects at Kπ mass beyond 1500 MeV is made. In particular, the recently reported state at 1800 MeV is discussed. A B5-model analysis of the reaction K−p→K¯0π−p is also presented.
NORMALIZED TO SIG(K- P --> ANYTHING) OF 24.3 +- 0.8 MB.
FORWARD CROSS SECTION OPTICAL POINT FROM TWO PARAMETER EXPONENTIAL FIT OVER 0.12 < -T < 0.68 GEV**2.
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Results are presented on a series of measurements of ρ-photoproduction from hydrogen, deuterium, and complex nuclei ranging up to lead, at photon energies ranging from 4 to 9 GeV. Detailed dipion mass-spectrum fits are presented, using a Drell-type nonresonant background and its interference with the resonant amplitude, with no other arbitrary backgrounds. For hydrogen and deuterium, the inelastic contributions have been subtracted. The A dependence of the cross sections is analyzed to yield values of γρ24π and σρN at average photon energies of 6.1, 6.5, and 8.8 GeV. The hydrogen-to-deuterium ratios indicate the presence of possible nondiffractive amplitudes at low energies which then decrease with energy.
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