Quasi-inclusive and total inclusive ϱ + , ϱ − and ϱ 0 cross sections have been studied, using data of a π + p and a pp bubble chamber experiment at 16 and 24 GeV/ c , respectively. In pp collisions it is found that the total inclusive cross sections for ϱ 0 , ϱ + and ϱ − production are about equal. This equality also holds for the differential cross sections d σ/ d y ∗ , all showing the characteristics of dominantly central production. In the π + p reactions the ϱ − are mainly produced centrally, whereas there are strong additional contributions in the beam fragmentation region for ϱ + and ϱ 0 mesons. In the central region, however, the cross sections for ϱ + , ϱ − and ϱ 0 production are almost equal within errors. All our findings agree with what is expected from quark model predictions.
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Measurements of inclusive cross sections at 100 GeV/c are presented for the double-charge-exchange reactions a+p→π−X with a=π, K, or p. The measurements covered a kinematic range in the Feynman x variable of 0.3<~x<~0.9 at transverse momenta of 0.3 and 0.5 GeV/c. A model summing the contributions from resonance production and from inclusive central-region π− production is used to fit the data and demonstrates the importance of resonance production via one-pion exchange for large values of the Feynman x.
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The inclusive reactions pn → p s + x and π + n → p s + x at incident momentum of 195 GeV/ c have been studied in an exposure of the Fermilab 30 inch deuterium filled bubble chamber to a mixed ( π + , p) beam. Analysing the t and M 2 dependence of our data within the framework of triple-Regge models we conclude that pion exchange yields a dominating contribution. Comparing our data with the pp results we conclude that isoscalar Regge exchange, ω, is much larger than isovector, ϱ, Regge exchange. We observe significant leading π − emission from the recoiling mass x, comparable to that observed in on-mass-shell π − p → π − experiments. This verifies our conclusions about pion-exchange dominance in the above reactions.
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The production of φ mesions is studied in the reaction π+p→π+p K+K− and π+→π+p K0K¯0 at 3.75 GeV/c. A large isotropic component is seen in the production angular distribution for the reaction π+p→π+pφ. The cross sections for the φπ+p and φΔ++ final states are compared with the cross sections for ωπ+p and ωΔ++ at the same momentum.
NORMALIZED TO THE CROSS SECTION FOR PI+ P --> PI+ P PI+ PI-.
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The inclusive production of antiprotons and Λ's in e+e− annihilation has been measured as a function of the c.m. energy in the range 3.7-7.6 GeV. We find that the baryon cross section has a behavior different from the total hadronic production. Our results show a rapid rise in the ratio σp¯σμμ between 4.4 and 5 GeV, consistent with what would be expected from charmed baryon production. Λ¯ production is 10-15% of p¯ production at all energies.
NOT INCLUDING SYSTEMATIC ERRORS.
We have measured the charge-exchange reaction pp → (p π + ) (p π − ) at s = 23, 31, 45, 53, and 63 GeV at the ISR, using the Split Field Magnet detector. The data are characterized by a sharp forward peak of width 0.02 (GeV/ c ) 2 , followed by a much gentler slope at higher | t |; sizeable Δ ++ , Δ 0 , and N 0 production is observed in the (Nπ) mass spectra. Two different components are present in the data following power-law energy dependence of the type p lab − n with n 1 = −1.63 ± 0.13 and n 2 = −0.96 ± 0.07, respectively, indicating the onset of mechanisms in competition with pion exchange at ISR energies.
CHARGE EXCHANGE DOUBLE DIFFRACTION DISSOCIATION OF PROTONS. DEL++, DEL0, N(1520)0 AND N(1688)0 RESONANCES IDENTIFIED IN PROTON-PION MASS SPECTRA.
We report results on a new measurement of the double diffractive reaction pp → (p π + π − ) (p π + π − ) at the ISR obtained with the Split Field Magnet detector. Experimental procedures and data analysis are discussed in detail. The cross section measured at the five standard ISR energies exhibits an increase of (55 ± 7)% in the s -range from 549 to 3892 GeV 2 .
DOUBLE DIFFRACTION DISSOCIATION OF PROTONS.
New experimental results on the reactions K L 0 p→K S 0 p, Λπ + , Σ 0 π + andΛπ + π 0 at c.m. energies between 1.54 and 1.71 GeV are presented. This experiment has a statistical accuracy comparable with or greater than corresponding K − p and K − d experiments in the same energy range and a comparison with the data from these different types of experiments has been made. A search has been made for narrow states with masses in the region of 1.58 GeV.
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FOR THE FPRIME A PURE 2+ STATE IS ASSUMED AND ONLY JZ=+1,0,-1 CONTRIBUTIONS ARE CONSIDERED.
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The vector meson production, hypercharge exchange reactions K − p → ( φ , ω , ϱ ) Λ and ( φ , ϱ ) Σ 0 are studied at 4.2 GeV/ c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of ∼ 120 events/μb. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology.
ERRORS INCLUDE THE 5 PCT MODEL ERROR BUT NOT THEORETICAL RESONANCE PARAMETRIZATION ERRORS.
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