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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The first results on inclusive photoproduction of π 0 at transverse momenta up to 4 GeV/ c , using incident γ energies between 50 and 150 GeV are presented. A comparison is made with inclusive π 0 production obtained, in the same experiment, with incident π − . Using the π − data to parametrize the hadronic behaviour of the photon, significant differences are observed in quantitative agreement with QCD Compton scattering and corrections thereof.
FC,IC,BC REFER TO FORWARD,INTERMEDIATE AND BACKWARD CALORIMETERS.
FC,IC,BC REFER TO FORWARD,INTERMEDIATE AND BACKWARD CALORIMETERS.
The charged particle multiplicity distribution for e + e − annihilations at s = 29 GeV has been measured using the High Resolution Spectrometer at PEP. The multiplicity distribution, expressed as a function of the mean, shows KNO scaling when compared to e + e − data at other energies. Multiplicity distributions for particles selected in different central rapidity spans are presented. All of these are well presented by the Negative binomial distribution. As the rapidity span is narrowed, the distributions become broader and approach a constant value of the parameter k .
KNO charged multiplicity distributions for the Inclusive Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
Folded rapidity distribution measured along the thrust axis of the event. Errors are dominated by systematics. All charged particles are assigned the pion mass.
KNO charged multiplicity distribution for the Two Jet Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
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