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.
No description provided.
SIG = 4*PI*LEG(L=0).
FORWARD DIFFERENTIAL CROSS SECTION CALCULATED FROM LEGENDRE POLYNOMIAL COEFFICIENTS AND ERROR MATRICES.
We have performed a search for narrow resonances in the center of mass energy range from 29.90 to 31.46 GeV using the e + e − storage ring PETRA at DESY. We present the total cross section for hadron production and an upper limit for resonance production, indicating that no bound state of charge- 2 3 quarks exists in this energy range.
AVERAGE VALUE OF R OVER THE SCAN REGION.
THESE MEASUREMENTS COMBINED WITH PREVIOUS DATA AT 30.0 AND 31.6 GEV REPORTED IN CH. BERGER ET AL., PL 86B, 413 (1979).
A dipion enhancement of mass 1.59 GeV and width 0.23 GeV is observed in the channel γp→π + π − p. The spin-parity of the enhancement is consistent with being 1 − .
No description provided.
A search for narrow resonances in e + e − annihilation at c.m. energies between 29.90 and 31.46 GeV provides no evidence for the existence of such states. The 90% confidence upper limit on the integrated resonance cross section is 38 nb MeV, significantly below the value expected for the lowest (t,t̄) bound state.
No description provided.
This report reviews the experimental investigation of high energy e + e − interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the on-line data collection and the off-line analysis are also outlined. Results are presented on tests of quantum electrodynamics using e + e − → e + e − , μ + μ − and τ + τ − , on the measurement of R , the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant α s .
SUMMARY OF RESULTS FOR R FROM TOTAL OF 2595 HADRON EVENTS. INCLUDES RED = 1046, 1079, 1072 AND 1114.
MEAN THRUST AND THRUST DISTRIBUTION (1/N)*DN/DTHRUST AT 13, 17, 22 AND 30 GEV. SOMEWHAT DETECTOR DEPENDENT. INCLUDES RED = 1079 AND 1072. SEE ALSO RED = 1114. ALSO JET ANALYSIS USING FOX-WOLFRAM MOMENTS.
OBLATENESS DISTRIBUTION AT 17 AND 27.4 TO 31.6 GEV. SEE RED = 1146.
None
No description provided.
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No description provided.
DOMINANT NATURAL PARITY EXCHANGE.
EVIDENCE FOR FORWARD DIP FOR -TP < 0.1 GEV**2.
In a high statistics (90 events/μb) bubble chamber experiment, the reactions π − p→K s 0 K ± π ∓ n have been studied at 3.95 GeV/ c . A significant enhancement is observed in the ( K K π) system which we attribute to the production of the E(1420) meson. For its mass, M , and width, Λ, we find M =1426±6 MeV and Γ =40±15 MeV. The E(1420) quantum numbers are determined to be I G J P =0 + 1 + with a branching ratio E → K ∗ K + c.c E →[δπ+( K ∗ K + c.c. )]=0.86±0.12 , where δ→ K K . The cross section for the reaction π − p→En, with E→K 0 K ± π ± , is 8.2±1.0 μ b. Forward and backward productions are observed in the approximate ratio 2:1. The SU(3) assignment of the E(1420) meson is discussed.
BACKGROUND SUBTRACTED.
No description provided.
No description provided.
Data from the MARK-J detector on the reactions e+e−→μ+μ−, τ+τ− in the center-of-mass energy range from 12 to 36.7 GeV are presented. The μ, τ radii are shown to be <10−16 cm. A search has been made for the production of a new heavy lepton and for the production of spin-0 supersymmetric partners of the muon. 95%-confidence-level lower limits of 16 GeV for the mass of a new charged heavy lepton and 15 GeV for the mass of the scalar partners of the muon are obtained.
No description provided.
The ϒ, ϒ′, and ϒ′′ states have been observed at the Cornell Electron Storage Ring as narrow peaks in σ(e+e−→hadrons) versus beam energy. Data were collected during a run with integrated luminosity of 1000 nb−1, using the Columbia University-Stony Brook segmented NaI detector. The measured mass differences are M(ϒ′)−M(ϒ)=559±1(±3) MeV and M(ϒ′′)−M(ϒ)=889±1(±5) MeV, where the errors in parentheses represent systematic uncertainties. Preliminary values for the leptonic width ratios were also obtained.
HADRONIC EVENTS/SMALL-ANGLE BHABHA YIELD.
Forum