The inclusive jet cross section has been measured in the UA1 experiment at the CERN p p Collider at centre-of-mass energies √ s = 546 GeV and √ s = 630 eV. The cross sections are found to be consistent with QCD predictions, The observed change in the cross section with the centre-of-mass energy √ s is accounted for in terms of x T scaling.
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Evidence for narrow states produced by Σ − interactions in beryllium, and decaying into ( Λ p + pions ), has been obtained in an experiment at the CERN SPS hyperon beam. At 3.1 GeV/ c 2 , the ( Λ p π + π + ), ( Λ p π + π + π − ) and ( Λ p π + π − ) effective mass distributions show an excess of 45, 19 and 62 events above a background of 50, 28 and 187, respectively. The possibility that these three signals are statistical fluctuations is remote. The observed widths of the signals are compatible with the mass resolution of the apparatus, 24 MeV/ c 2 FWHM. We have not been able to find an interpretation of the quantum numbers of the final states, which are baryon number 0, strangeness −1 and charge +1, 0 and −1.
The cross section times branching fraction. The differential cross section is fitted by the equation : D3(SIG)/D3(P) = (1-XL)**POWER*EXP(-SLOPE*PT**2).
We use the reaction e+e−→hadrons, in the Mark J detector at the DESY electron-positron collider PETRA, to determine the hadronic cross section up to 46.78 GeV. The production of a top quark with a charge equal to (2/3) is excluded up to 46.6 GeV with 95% C.L. The observed rise in the cross section at higher energies is consistent with the electroweak prediction for a Z0 mass of 93 GeV. We describe some unusual muon inclusive events.
Errors are statistical only.
Energy scan of R.
Inclusive muon cross section.
Inclusive production cross sections have been measured for the processes p+A→Ξ0+X (A=Be, Cu, Pb) and for p+Be→Ξ¯0+X. Data were taken at angles of 0, 2, 3.5, 7.3, and 9.8 mrad between the incident 400-GeV proton beam and the outgoing hyperon beam. Production cross sections for Λ and Λ¯ production were measured at the same time. The A dependence of the Ξ0 cross sections is discussed, along with interpretations in terms of various models.
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Experimental multiplicity distributions scaled in the Koba-Nielsen-Olesen (KNO) form for hadron-nucleus interactions show clear deviations from the scaling distribution observed for hadron-hadron interactions. The deviations become larger as A increases. Our data can be described by a model which invokes the hypothesis that KNO scaling is valid for hadron-nucleus interactions at a fixed impact parameter. In this model, the A dependence of the multiplicity distributions results from the convolution of scatterings at various impact parameters.
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Results are presented on inclusive production of ∑+(1385) and ∑−(1385) inK−p interactions at 110 GeV/c. The inclusive and topological cross sections have been estimated and compared with published results at lower energies. The inclusive cross section of ∑+(1385) seems to decrease with c.m. energy, while that of the ∑−(1385) is nearly constant. The mean charged multiplicity associate to Σ(1385) increases with c.m. energy. The ∑+(1385) is produced both in the target fragmentation region and in the central region where ∑−(1385) is predominantly produced in the central region. Approximately 16% of the Λ's stem from the decay of ∑±(1385) and the kinematic distributions of these Λ's are not very different from the inclusive Λ's.
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Data are presented for the exclusive reaction pp → pp π+ π− at\(\sqrt s= 62GeV\) with two leading protons at large Feynman-x and a centrally produced π+;π− system. In this kinematical configuration one expects a substantial contribution from Double Pomeron Exchange, which is a potential source of glueballs. The experiment was performed at the CERN ISR using the Split Field Magnet spectrometer. In the mass range between 1,000 and 1,700 MeV/c2 the invariant mass distribution for the central π+;π− system exhibits a very significant signal for thef0(1270) and no other obvious resonant states.
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The multiplicities per event of π ± and K ± are measured separately for e + e - annihilation into c c , b b , and light quark pairs at E cm=29 GeV. The K ± multiplicity is higher for heavy quark events than for light quark events. The π ± multiplicity and the π ± scaled differential cross section at low x = E beam/ E beam are found to be higher for b b events than for other events.
Numerical values requested from authors. Data given separately for (b bbar), (c cbar) and light quark jets.
Measured multiplicities for (b bbar) jets.
Measured multiplicities for (c cbar) jets.
The first data on the production of D ∗ (2010) are presented as observed in π − -proton interactions at √ s = 27 GeV . It is found that D ∗ (2010) dominates the total charm D-meson production, without a significant non-central component.
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