This Letter reports measurements of the ratios of $\pi$, K, and p production at large values of transverse momentum in $\pi^- −p$ collisions. The charge ratios, such as $\frac {\pi^−} {\pi^+}$, $\frac {K^−} {K^+}$, and $\frac {\overline{p}}{p}$ are seen to be quite different from those measured in p −p collisions. These ratios are sensitive tests of hard-scattering models, and are compared with theoretical predictions. The particle ratios have also been studied as a function of center-of-mass angle ($\theta^*$) at $\theta^*$ = 90°, 77°, and 60°.
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Measurements have been made of the polarisation parameters G and H for the process γ p→ π + n in the photon energy range 600–1875 MeV and pion c.m. angles between 30° and 100°. These data were obtained in a double polarisation experiment, in which the polarised photon beam from the Daresbury electron synchrotron was incident upon a polarised proton target. Theoretical predictions from a current analysis are compared with the data.
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Experimental results on the reaction π − p → K ∗0 (890) X 0 at 10 GeV /c are presented. By using the K ∗0 polarization measurements, a detailed study of the production has been carried out as a function of the missing mass squared and of the four-momentum trasnfer squared to the K ∗0 . We found that: (a) K ∗0 production is dominated by natural parity exchange; (b) K ∗0 helicity-zero production dominates the unnatural parity exchange contribution and (c) the main features of the reaction are in agreement with the predictions of the finite mass sum rules.
TO TAL (NATURAL+UNATURAL PARITY EXCHANGE) CROSS-SECTIONS.
NATURAL PARITY EXCHANGE CROSS-SECTIONS.
UNATURAL PARITY EXCHANGE CROSS-SECTIONS.
Three narrow resonances have been observed in e+e− annihilation into hadrons at total energies between 9.4 and 10.4 GeV. Measurements of mass spacing and ratios of lepton pair widths support the interpretation of these "ϒ" states as the lowest triplet-S levels of the bb¯ quark-antiquark system.
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Total and semi-inclusive cross sections, longitudinal and transverse momentum distributions and spin density matrix elements of theK*+(892) andK*0(892) produced in the inclusive reactionsK+p→K*+(892)+X andK+p→K*0(892)+X at 32 GeV/c are studied in detail. The inclusive spectra of theK*(892) and their decay products are compared with pion and neutral kaon production. TheK*+(892) andK*+(892) are dominantly produced by kaon fragmentation processes. The dependence of average transverse momentum <pT> vs.x for resonances has been investigated for the first time.
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This paper presents the results of a study of the dominant neutral final states from π−p interactions. The data were obtained in an experiment performed at the Brookhaven National Laboratory Alternating Gradient Synchrotron, using a set of steel-plate optical spark chambers surrounding a liquid-hydrogen target. We present differential and total cross sections for the reactions (1) π−p→n+π0 and (2) π−p→n+η0(η0→2γ) and total cross sections for the reactions (3) π−p→n+kπ0 (k=2, 3, 4, and 5) and (4) π−p→all neutrals for eighteen values of beam momentum in the interval 1.3 to 4.0 GeV/c. The angular distributions for (1) and (2) have been analyzed in terms of expansions in Legendre polynomials, the coefficients for which are also given.
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SIG = 4*PI*LEG(L=0).
FORWARD DIFFERENTIAL CROSS SECTION CALCULATED FROM LEGENDRE POLYNOMIAL COEFFICIENTS AND ERROR MATRICES.
The production of K S 0 , Λ and Λ in π − p ractions at 16 GeV/ c is investigated. Cross sections for single strange particles are determined, both inclusively and as functions of the charged multiplicity. Some characteristics of the multiplicity distributions are also discussed. Inclusive distributions are studied as a function of the longitudinal and transverse variables of V 0 and the missing mass squared. The average charged multiplicities of the systems recoiling against the Λ and K S 0 are presented.
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Results are presented from a study of inclusive neutral strange particle production by a 147 GeV/ c tagged π + /K + /p beam in the Fermilab 30-inch hydrogen bubble chamber. The experiment made use of the proportional hybrid spectrometer system. Results are based on 995 K S 0 , 485 Λ, and 83 Λ found in a sample of 132 000 pictures. Cross sections are given for inclusive production of these particles by each of the three beam particles, and comparisons are made with measurements at other energies. Topological cross sections are also calculated, and KNO multiplicity scaling is investigated. Distributions are presented of invariant cross sections as functions of the Feynman scaling variable x and c.m. rapidity y . The transverse momentum-squared distributions with their fitted slopes are also given. Comparisons are made of the production characteristics for the three beam types.
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We present results on an amplitude analysis of the K + K − system produced in the reaction π − p→K + K − n from threshold up to 2.2 GeV. The branching ratios of f 0 and f' to K K have been determined. In the low mass region of the K K system the observation of an S-wave enhancement at 1.3 GeV and the interference of the f 0 -A 2 -f' mesons are studied. We observe a 3 − structure in the mass region of 1.7 GeV which is consistent with g 0 production. With this interpretation the branching ratio g→ K K has been determined. Evidence for a new structure in the J p = 2 + wave around 1.8 GeV with a width of ∼200 MeV is presented.
HELICITY ZERO D-WAVE AMPLITUDE FITTED BY SUM OF BREIT-WIGNER RESONANCES. F 14 GIVES T-DEPENDENCE. ALSO EVIDENCE FOR 1.8 GEV STATE WITH 0.60 +- 0.13 MUB PRODUCTION CROSS SECTION.
FROM HELICITY ZERO F-WAVE AMPLITUDE ASSUMING PREDOMINANTLY G(1680)0 PRODUCTION. F 16 GIVES T-DEPENDENCE.
Lambda production is studied in K − p interactions at 32 GeV/ c . The total Λ cross section is 2.31±0.03 mb . Using the measured Λγ combinations we find that (31±4)% of all Λ's are produced via the Σ 0 → Λγ decay. About 60% of the Λ's are associated with either a N N or K K pair; about 40% of the Λ's are produced through the hypercharge annihiltion reaction K − p→ Λ + π 'a. The two-peak structure of the invariant x distribution can be related to fragmentation processes. The Λ is found to be unpolarized in the target fragmentation region, whereas a transverse polarization is observed for forward produced Λ's. As a function of p ⊥, a polarization effect is measured at medium p ⊥.
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