We report results from a study of π−p→ω0n at 6.0 GeV/c based on 28 000 events from a charged and neutral spectrometer. Background under the ω0 is only 7%, a large improvement over deuterium-bubble-chamber work. Density matrix elements, projected cross sections, and effective trajectories for natural and unnatural exchanges are presented.
Differential cross sections for the elastic scattering of negative kaons on protons are presented for 19 momenta between 1.732 GeV/ c and 2.466 GeV/ c . The general features of the cross sections are discussed.
We report on measurements of inclusive π 0 production at c.m. energies of 53 and 63 GeV, θ ≅90°, from p-p collisions at the CERN ISR. In the range 0.2< x t <0.45 the data can be described by a form: Ed 3 σ d p 3 ∝p − (6.6±0.8) t (1−x t ) (9.6±1.0) .
The reactions π+p→Σ+(1385)K+ and π+p→Σ+(1385)K*+(890) are examined. The Σ+(1385)K+ differential cross section for −t′<0.5 GeV2 and spin density matrix elements agree with a Regge-pole model incorporating (nondegenerate) vector and tensor K* exchange with dominant M1 coupling. The Σ+(1385)K*+(890) density matrix elements are consistent with the quark-additivity predictions. A Y*+ at a mass of 1700 MeV is also observed in the Λπ+ mass distribution, produced opposite both K+ and K*+(890).
We have measured the differential cross section for π−p→η0n at 6.0 GeV/c from 6730 very clean events in which the decay η→π+π−π0 was detected. The high statistics reveals a sizable forward turnover, implying a dominance of the helicity-flip amplitude. A precisely determined A2 trajectory, linear for |t|<1.0 (GeV/c)2, is found from combining our data with those at energies up to 101 GeV.
A measurement of the coherent regeneration amplitude in carbon in the energy range 30-130 GeV is presented. The results are consistent with the dominance of this process by ω exchange, and a precise value of the intercept of the ω trajectory is obtained: αω(0)=0.390±0.014.
We have determined the coherent KS regeneration amplitudes on various nuclei, from 20 to 140 GeV/c, using a particularly systematics-free technique. Our results are well represented by |(f−f¯)k|=2.23A0.758p−0.614 mb. This p dependence corresponds to an effective "nuclear" intercept ``αω(0)''=0.386±0.009, whereas the elementary value is αω(0)=0.44±0.01. Comparisons are made with data below 25 GeV/c, and with optical-model predictions. The latter work only if "αω(0)" is postulated to hold for the elementary amplitudes.
Precise measurements att=0 of the KLp→KSp amplitude (modulus and phase) were made. Over 50000 Kπ2 decays along with normalizing Kμ3 events were detected behind a 7.2-m-long liquid-hydrogen regenerator. The momentum dependence of the modulus and phase are presented, and the results are combined with those of other experiments to extract the relevant parameters of ω exchange.
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