Mesons decaying into π 0 or η and one charged meson were studied using a liquid-argon calorimeter in a non-magnetic double-arm spectrometer. Cross sections and energy dependences are presented. The ϱ ± production mechanisms are discussed in detail: ω and π exchange contribute the largest fractions, but also A 2 exchange is present. ϱ ± production by ω exchange is shown to follow the energy behaviour predicted by the Regge trajectory α ω ( t ) = 0.4 − | t |.
Axis error includes +- 0.0/0.0 contribution (13 TO 25////STATISTICAL ERRORS ARE SMALLER THAN THE SYSTEMATIC ERRORS).
No description provided.
Λ∘ polarization in inclusive production by protons on iridium has been measured at 28.5 GeV/c over the region 0.55 GeV/c<~P⊥<~1.6 GeV/c. The polarization rises from (-12.6±5.5)% at 0.55 GeV/c to (-33.4±4.6)% at 1.6 GeV/c. Significant differences from previous measurements at other energies with different targets are observed, particularly at low P⊥.
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Results are presented on vector meson production in the hypercharge exchange reactions: π + p → K ∗+ (890) Y + and K − p→ ρ − Y + where Y + is either Σ + or Y ∗+ (1385). These reactions have been studied at 7 GeV/ c and 11.5 GeV/ c using the SLAC Hybrid Facility. Total and differential cross sections, hyperon polarization, and vector meson decay angular distributions are presented. We find that reactions with Σ + production are dominated by natural parity exchange. The Y ∗ (1385) reactions are consistent with substantial natural parity exchange contributions but also show significant unnatural parity exchange. The differential cross sections and polarization measurements for the vector meson production are compared to the pseudoscalar production reactions.
Axis error includes +- 20/20 contribution.
Axis error includes +- 20/20 contribution.
Axis error includes +- 20/20 contribution.
Inclusive production of vector and tensor mesons is studied in a K − p experiment at 32 GeV/ c in the MIRABELLE bubble chamber. The K ∗ 0 (890) , ϱ 0 and ω cross sections are comparable, about 4 mb each. The K ∗ 0 (1420 and cross sections are also comparable, about 1 mb each. The K ∗ o ̈ + (890), Φ, K ∗ o ̈ − (1420) and f cross sections beam fragmentation; ϱ production is almost forward-backward symmetric in the c.m.s. The p T production slopes of K ∗ o ̈ − (890) and ϱ are similar, the Φ slope is shallower. Vector and tensor mesons alone are responsible for ≅50% (≅60%) of final-state pions
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We have studied inclusiveΔ++ (1232),∑+ (1385), and∑− (1385) baryon resonance production inK−p interactions at 32 GeV/c. The inclusive and topological cross sections are estimated and compared with published results at lower energies. No energy variation of the cross section is observed forΔ++ (1232) and only a slight decrease is seen in case of∑± (1385). The production properties are investigated through longitudinal and transverse momentum distributions. TheΔ++ (1232) is dominantly produced in the target fragmentation region. The∑+ (1385) is produced both in the target fragmentation region and in the central region, while the∑− (1385) is predominantly produced in the central region. About 20% of the final state protons are produced via aΔ++ (1232) decay and about 25% of the Λ produced come from the decay of∑+ (1385) and∑− (1385).
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We have measured in a single experimental setup, the differential cross sections and decay angular distributions of the Y ∗ (1385) produced in the two line-reversed reactions: π + p → K + Y ∗+ (1385) (279 events/ω b ) and K − p → π − Y ∗+ (1385) (190 events/ωb) at 11.5 GeV/ c . The data have been derived from a triggered bubble-chamber experiment using the SLAC Hybrid Facility. We find the differential cross sections and Y ∗ polarizations for the two reactions to be in agreement with exchange-degeneracy predictions, if kinematic differences are taken into account. The Stodolsky-Sakurai and additive quark model predictions are in agreement with the main features of the decay angular distributions of the Y ∗ (1385), except for small violations at low momentum transfer, which can be associated with a finite helicity non-flip contribution in the forward direction.
Axis error includes +- 10/10 contribution.
THESE FINAL DIFFERENTIAL CROSS SECTIONS ARE INCLUDED IN THE RECORD OF J. BALLAM ET AL., PRL 41, 676 (1978).
TRANSVERSITY AMPLITUDES FOR SIG(1385P13)+ PRODUCTION. THE IMAGINARY PARTS OF T(11) AND T(-1-1) WERE ARBITRARILY FIXED AT ZERO.
Inclusive η photoproduction has been studied at 9.7 GeV, on hydrogen and deuterium targets. A simple, parameter-free ρ0-dominance model adequately fits the forward cross sections, but overestimates the cross section at large momentum transfer.
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We have measured in a single experimental setup the differential cross sections and polarizations of the Y*(1385) produced in the two line-reversed reactions π+p→K+Y*(1385) (260 eV/μb) and K−p→π−Y*(1385) (180 eV/μb) at 11.5 GeV/c. We compare these results to Σ+ production in the same experiment. The data have been derived from a triggered bubble-chamber experiment using the SLAC Hybrid Facility. We find that both helicity-flip-dominated (Y*) and helicity-nonflip-dominated (Σ) processes are consistent with weak-exchange-degeneracy predictions.
Axis error includes +- 10/10 contribution.
Axis error includes +- 10/10 contribution.
Axis error includes +- 10/10 contribution.
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THE DATA POINTS AT -T = 0.40 AND 0.60 GEV**2 WERE OBTAINED FROM THE PAPER BY J. P. DE BRION ET AL., NP B32, 557 (1971). THESE DATA OF O. GUISAN ET AL., PL 18, 200 (1965) ARE USED TO DETERMINE THE ABSOLUTE NORMALIZATION.