The angular distributions of K<sup loc="post">+</sup>p and π<sup loc="post">+</sup>p backward elastic scattering have been measured at 5.2 and 6.9 GeV/c. Backward π<sup loc="post">-</sup>p and K<sup loc="post">-</sup>p elastic scattering were studied at 6.9 GeV/c. Backward peaks are observed in K<sup loc="post">+</sup>p scattering with an energy dependence of the form s<sup loc="post">−4</sup>.
No description provided.
The transmission regeneration amplitude after a thick copper block has been measured. The quantity {∣ƒ(0)- overlineƒ(0)∣ }/{k} varies from 20.0 $\pm$ 1.4 mb at 2.75 GeV/c to 13.6 $\pm$ 1.2 mb at 7.25 GeV/c. Results are in agreement with optical model calculations in which real and imaginary parts of the amplitudes for single nucleon scattering are determined from forward dispersion relations and total cross-sections.
Regeneration amplitude.
We studied 21 187 two-prong, two-prong-with-kink, and zero-prong-V events at incident kaon momentum of 1.33 GeVc using the 72-in. hydrogen bubble chamber at the Lawrence Radiation Laboratory and two scanning and measuring projectors in Urbana. We determined the total and partial cross sections for all contributing reactions. For the two-body final states, some production and polarization angular distributions were measured. The angular distributions are discussed in terms of exchanges in the kinematical channels s, t, and u assuming the simplest Feynman graphs. Elastic scattering is analyzed as a diffraction process.
No description provided.
Differential cross sections as a function of momentum are presented for the production of K+ mesons in p−p collisions at incident proton energies of 2.54, 2.88, and 3.03 GeV. The measurements were made at 20°, 30°, and 40° relative to the direction of the internal proton beam of the Princeton-Pennsylvania accelerator. At 2.54 GeV, the results follow closely the predictions from phase space (with 60% K+ΣN and 40% K+Λp in the final state). At 2.88 and 3.03 GeV, however, there is a definite disagreement with phase space. The data are compared to the predictions of three models: (1) a model based on the assumption that K's are produced via p+p→K++X+, where X+ is a B=2, S=−1 resonance which decays into a nucleon+hyperon; (2) the isobar model; and (3) the one-pion-exchange model. Model (1) is found to be inconclusive, model (2) is inadequate, and model (3) is partly successful in predicting total cross sections, but not in interpreting the detailed experimental observations.
No description provided.
No description provided.
No description provided.
We present the results of a spin determination of the g 1 − (1640) meson from an analysis of its dipion decay mode (π − π 0 ), and find that spin three (or maybe greater) is favored [1,2]. We also report on the observation of an isospin one KK̄ enhancement at 1640 MeV which is consistent with a new decay mode of the g meson. A relative branching ratio of (K K ̄ /ππ) = 8 ± 3 8 % is obtain from our analysis.
The values of the cross sections were presented for reactions with KS finalstates for visible KS decays only.
The cross section value is corrected for invisible KS decay.
The cross sections for the two antiproton-proton annihilation-in-flight modes, ˉp + p → π+ + π- ˉp + p → k+ + k- were measured for fifteen laboratory antiproton beam momenta ranging from 0.72 to 2.62 GeV/c. No magnets were used to determine the charges in the final state. As a result, the angular distributions were obtained in the form [dσ/dΩ (ΘC.M.) + dσ/dΩ (π – ΘC.M.)] for 45 ≲ ΘC.M. ≲ 135°. A hodoscope-counter system was used to discriminate against events with final states having more than two particles and antiproton-proton elastic scattering events. One spark chamber was used to record the track of each of the two charged final particles. A total of about 40,000 pictures were taken. The events were analyzed by measuring the laboratory angle of the track in each chamber. The value of the square of the mass of the final particles was calculated for each event assuming the reaction ˉp + p → a pair of particles with equal masses. About 20,000 events were found to be either annihilation into π ±-pair or k ±-pair events. The two different charged meson pair modes were also distinctly separated. The average differential cross section of ˉp + p → π+ + π- varied from ~ 25 µb/sr at antiproton beam momentum 0.72 GeV/c (total energy in center-of-mass system, √s = 2.0 GeV) to ~ 2 µb/sr at beam momentum 2.62 GeV/c (√s = 2.64 GeV). The most striking feature in the angular distribution was a peak at ΘC.M. = 90° (cos ΘC.M. = 0) which increased with √s and reached a maximum at √s ~ 2.1 GeV (beam momentum ~ 1.1 GeV/c). Then it diminished and seemed to disappear completely at √s ~ 2.5 GeV (beam momentum ~ 2.13 GeV/c). A valley in the angular distribution occurred at cos ΘC.M. ≈ 0.4. The differential cross section then increased as cos ΘC.M. approached 1. The average differential cross section for ˉp + p → k+ + k- was about one third of that of the π±-pair mode throughout the energy range of this experiment. At the lower energies, the angular distribution, unlike that of the π±-pair mode, was quite isotropic. However, a peak at ΘC.M. = 90° seemed to develop at √s ~ 2.37 GeV (antiproton beam momentum ~ 1.82 GeV/c). No observable change was seen at that energy in the π±-pair cross section. The possible connection of these features with the observed meson resonances at 2.2 GeV and 2.38 GeV, and its implications, were discussed.
No description provided.
No description provided.
The Λ polarization and the differential cross section for the reaction γ+p→K++Λ have been measured, using the Caltech synchrotron, at 90° in the c.m. system and at laboratory photon energies of 1100, 1200, and 1300 MeV. Protons from the asymmetric decay of the Λ were detected by counters placed above and below the production plane. Kaons were identified by their behavior in a thick range telescope. Polarization results were PΛ=+0.34±0.09 at 1100 MeV, +0.30±0.07 at 1200 MeV, and +0.08±0.07 at 1300 MeV, where PΛ was measured in the p^γ×p^Λ direction. The differential cross section was constant with energy at 0.14±0.01 μb/sr. Although the apparent bump in the polarization at 90° at a total energy of ≈1700 MeV adds support to models which invoke a resonance here, no really new conclusions can be reached.
No description provided.
No description provided.
The differential cross sections for the photoproduction reactions γ+p→π++n, γ+p→K++Λ0, and γ+p→K++Σ0 have ben measured for incident laboratory photon energies between 3.4 and 4.0 GeV and for meson center-of-mass angles from about 25° to 45°. The reactions were studied by observing only the charged mesons. The momenta, velocities, and angles of the mesons were measured with a magnetic spectrometer, and the equivalent of nearly monochromatic gamma rays was obtained by performing bremsstrahlung subtractions. The cross sections agree with the inequality predicted from unbroken SU(3). The measured behavior of dσdt as a function of t shows similarities to that observed in studies of mesonnucleon scattering.
No description provided.
No description provided.
No description provided.
We have analyzed 2560 events in the final-state K O 1 K O 1 n produced in π − p interactions at 5, 7 and 12 GeV/ c . We observe the S ∗ (1070), f O and A 2 decaying into K O 1 K O 1 . Resonance parameters, cross sections, and branching ratios are given.
Cross section times branching ratio.
An analysis of the reaction K−p→K−pπ+π− at 2.0-GeVc incident momentum is presented. The total cross section for the reaction is 627±20 μb, based on 4519 events. The reaction is dominated by resonance production through several channels which overlap kinematically but do not appear to interferesubstantially. A maximum-likelihood procedure was used to determine the production fractions, which for the major channels are 0.44±0.02 for N*++(1236), 0.145±0.02 for Y*0(1520), 0.10±0.03 for N*+(1688), and 0.20±0.02 for simultaneous K¯*0N*0. Evidence is presented for the production of Y*+(1765) and its decay into Y*0(1520) as well as for production of Y*+(1660) with decay into K−pπ+. A four-standard-deviation enhancement is present at a K−π+ invariant mass of 690 MeV. Angular correlation data are presented for the N*++K−π−, Y*0π+π−, and K¯*0N*0 reaction channels. However, the difficulty of separating the various channels prevents a detailed study of the reaction dynamics.
No description provided.
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