We present evidence for the existence of two strange J P = 1 − mesons; one at 1410 MeV/c 2 coupling principally to K ∗ (892)π , and the other at 1790 MeV/c 2 couplingto K π , K ∗ π and ϱ K. The data derive from a partial wave analysis of the K 0 π + π − system produced in the reaction K − p → K 0 π + π − n at 11 GeV /c . The production mechanism and quark model assignment of each state are discussed. The state at 1410 MeV/c 2 most naturally understood as the first radial excitation of the K ∗ (892), and the 1790 MeV/c 2 object can be interpreted as the triplet D wave partner to the 3 − K ∗ (1780).
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Light ion collisions with carbon target at 4.2 GeV/c/N are studied. Pion multiplicity distributions, momentum and angular spectra are analysed. These data are described in terms of models assuming independent interactions of nucleons from the projectile nucleus with the target.
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The CDHS neutrino detector has been used to measure events originating in a tank of liquid hydrogen and in the iron of the detector. Total cross-sections, differential cross-sections, and structure functions are given for hydrogen and compared with those in iron. The measurements are in agreement with the expectations of the quark parton model. No significant differences indicative of nuclear binding effects in corresponding structure functions of protons and iron are observed. This may be of special interest in the case of the sea structure functions, since large differences are expected in some models.
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Results of a search for a predicted enhancement of several microbarns in the charm-photoproduction cross section just above threshold are reported. No charm decays were detected, from which an upper limit to the charm cross section of 94 nb (90% C.L.) at Eγ≃10 GeV was obtained. Upper limits in the range 270 to 450 nb were also obtained for the peak cross sections for threshold enhancements in γp→D−Σc++ and similar channels.
UPPER LIMIT TO AVERAGE CHARM CROSS SECTION.
UPPER LIMITS TO INDIVIDUAL CHANNELS.
We present the first results on the production of fast (p>10 GeV/c)p,\(\bar p\), Λ and\(\bar \Lambda \) from π± hydrogen and nucleus interactions at 30 GeV/c using the CERN Ω′ spectrometer. We have used five nuclear targets (C, Al, Cu, Sn, Pb) to study theA-dependence of the inclusive particle distributions in the region 0.3<xF<0.6. The high statistical level of our experiment allows us to demonstrate the differentA-behaviour of baryon and antibaryon inclusive reactions. We relate this difference to the final state interaction inside a nucleus using the formation-zone model.
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The measurements of the z and p T 2 distribution of hadrons produced in the interactions of 200 GeV muons with copper and carbon nuclei are shown in different x Bj and virtual photon energy intervals. Effects of the jet scattering are seen at the lowest virtual photon energies while for energies above 70 GeV there is no evidence of these effects. Comparison with a theoretical model indicates that at high jet energies the parton fragmentation distance is greater than the nuclear radius and that the parton absorption cross section is less than 10 mb.
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We observe γγ → η′ production in the reaction e + e − → e + e − π + π − γ. We measure the product γ γγ ( η ′) B ( η ′ → ϱ 0 γ ) to be 1.14 ± 0.08 ± 0.11 keV. A first measurement of the γγ → η′ transition form factor is made for Q 2 up to 1 GeV 2 .
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We report measurements from the CLEO detector of the rate of Ξ and Λ production in e+e− interactions in the upsilon region. Hyperon production from the decay of the ϒ(1s) is compared with continuum e+e− data. The ratio of the production rates of Λ (and Λ―) to K0 (and K―0) on the ϒ(1s) is 0.21 ± 0.03, much larger than in the continuum, 0.07 ± 0.01. The ratios of the production rates of the Ξ and Λ are comparable, 0.10±0.02 [ϒ(1S)] and 0.07 ± 0.02 (continuum). We discuss some implications of the data for gluon and quark fragmentation models.
CONTINUUM IS ECM 10.38 TO 10.64 GEV.
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The production of electrons with very high transverse momentum has been studied in the UA2 experiment at the CERN\(\bar pp\) collider (\(\sqrt s\)=540 GeV). From a sample of events containing an electron candidate withpT>15 GeV/c, we extract a clear signal resulting from the production of the charged intermediate vector bosonW±, which subsequently decays into an electron and a neutrino. We study theW production and decay properties. Further-more, we refine our results on the production and decay of the neutral vector bosonZ0. Finally, we compare the experimental results to the predictions of the standard model of the unified electro-weak theory.
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