Dimuon production is studied in 217-GeV/c π−-hydrogen and π−-beryllium collisions with a lead-glass array to detect photons associated with the ψ. The ψ−γ mass spectrum shows a 2.6-standard-deviation excess of events above background at ∼3.5 GeV. This excess, if attributed to the decay χ(∼3.5)→ψγ, implies that 0.70±0.28 of the ψ's are produced via radiative decay of one of the χ states.
E*D(SIG)/D(XL) is fitted by (1-X)**POWER.
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Toward the goal of experimentally determining pp elastic scattering amplitudes at 6 GeV/c, we have measured a linear combination of triple-spin correlation parameters and also a linear combination of spintransfer parameters over the |t| range between 0.2 and 1.0 (GeV/c)2. A horizontally polarized beam (S direction) was obtained by precessing the spin of the polarized beam from the Argonne Zero Gradient Synchrotron using a superconducting solenoid. The target protons were polarized vertically (N direction) and the polarization of the recoil protons was measured with a carbon polarimeter. The results are consistent with the amplitude corresponding to π exchange being almost real and positive.
KSS = (S00S) AND HSNS = (SN0S) MEASURED HERE CONTAIN SMALL ADMIXTURES OF THE OTHER SPIN-TRANSFER AND TRIPLE-SPIN CORRELATION PARAMETERS RESPECTIVELY DUE TO THE POLARIZED TARGET MAGNETIC FIELD - SEE TEXT. MEAN VALUE OF HSNS OVER THIS T-RANGE IS 0.098 +- 0.085. PARITY CONSERVATION REQUIRES THE VANISHING OF THE PARAMETERS KSN, HSNN, (000S) AND DNS, WHILE (000N) MUST AGREE WITH THE SINGLE SCATTERING POLARIZATION PARAMETER (0N00).
The inclusive and semi-inclusive cross sections for K*±(890) and Σ±(1385) resonances are determined in p¯p interactions at 14.75 GeV/c. They account for a large fraction of the KS0 and Λ0 produced. The K*-resonance production also affects the low-pT2 distribution of inclusive KS0. The x distributions of the resonance production are studied in terms of a simple quark-recombination model.
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Charged- and neutral-particle production from 400-GeV/c pp collisions are measured simultaneously using the Fermilab 15-ft bubble chamber. The π0 and K0 cross sections are rising at Fermilab energies, while the Λ0 cross section remains fairly constant. Similarly, the average number of π0's and K0's increases as a function of the number of negative particles in an event, yet no such dependence is noted for the Λ0's. The ratio of average number of π0 to average number of π− per inelastic collisions is found to be constant at Serpukhov and Fermilab energies (40 to 400 GeV/c) and equal to 1.22±0.02. Cross sections for Σ0 and Σ¯0 production are measured and limits are found for η0 and ω0 production. Neutral- and charged-pion correlations are compared with five pion-production models.
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Inclusive V0 production in 6.5-GeV/c K−p interactions is studied using the ANL 12-ft-diameter hydrogen bubble chamber. The total cross sections for inclusive K¯0 and Λ0 production are σ(K¯0)=7.98±0.49 mb and σ(Λ0)=3.94±0.24 mb. Semi-inclusive differential cross sections are determined as functions of Feynman x and transverse momentum squared of the V0's and of four-momentum transfer to the V0. The average charge multiplicity, the ratio 〈nc〉D, and the correlation function f2cc for the neutrally charged hadronic system recoiling from the V0 are determined as functions of the mass of the recoiling system. Results are used to examine universal aspects of multiparticle production.
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We have studied inclusive KS0, Λ, and Λ¯ production and strange-resonance production in the reactions pp→(KS0, Λ, or Λ¯)+π±+anything at 405 GeV/c. The observed cross sections are 7.43 ± 0.45 mb for KS0, 4.01 ± 0.35 mb for Λ, and 0.63 ± 0.12 mb for Λ¯. From the analyses of the effective-mass distributions for the (KS0π±), (Λπ±), and (Λ¯π±) systems, the resonance production cross sections are determined as 4.1 ± 1.0 mb for K*+(890), 3.6 ± 1.0 mb for K*−(890), 3.4 ± 1.7 mb for K*±(1420), 0.67 ± 0.12 mb for Σ+(1385), 0.45 ± 0.09 mb for Σ−(1385), and 0.25 ± 0.08 mb for Σ¯±(1385). The inclusive total and differential cross sections are discussed in comparison with data at lower energies. The direct production cross sections for pseudoscalar, vector, and tensor K mesons are estimated to be 2.3 ± 1.2, 3.4 ± 1.0, and 1.7 ± 0.8 mb, respectively. Direct pseudoscalar-K-meson production accounts for less than one-third of the total inclusive kaon production. Evidence of vector-meson dominance in inclusive meson production at high energy is indicated.
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A sample of about 230000 events of the reaction pi /sup -/p to pi /sup +/ pi /sup -/n, measured with a magnetic forward spectrometer set up in an unseparated pi /sup -/ beam with a momentum of 63 GeV/c at the SPS has been analysed in terms of one pion exchange. The elastic pi /sup +/ pi /sup -/ cross section has been determined using an extrapolation to the pion pole in the mass range up to m( pi /sup +/ pi /sup -/)=4 GeV. The total pi /sup +/ pi /sup -/ cross section is obtained via the optical theorem. (7 refs).
INTEGRATED 2- S-WAVE INTENSITY FOR 1500 TO 1800 MEV, INCLUDING SIGNIFICANT BACKGROUND.
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The experimentally determined average charged-particle multiplicities, 〈nX〉, of the systems, X, produced in the following reactions for 147 GeV/c incident pion momentum are presented as functions of the square of the invariant mass of X, MX2, and of |t|:π−p→πfast−X, π−p→pX, π−p→Δ++X, π−p→(π−π+)ρ0X, and π−p→Λ0X. Details of the analysis are discussed. These data can be fit by the expression 〈nX〉=A+B ln MX2+C|t| and the coefficients obtained for B are equal within their uncertainties. C is significantly different from zero only for π−p→πfast−X. These results and 〈nX〉 data from other inclusive and total-inelastic-reaction studies are discussed in terms of a simple model which assumes contributions to 〈nX〉 from the target-fragmentation, the central, and the beam-fragmentation regions in the case of total-inelastic reactions. For inclusive reactions, either the beam or target fragmentation is replaced by an exchange-particle-fragmentation contribution. The s, t, and MX2 dependence of the parameters of the model are deduced from triple-Regge considerations. The data are found to be consistent with the model and values are presented for the parameters.
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