Inclusive production of Δ ++ (1232) with >| t p, Δ ++>|<0.6 (GeV/ c ) 2 is studied in 32 GeV/ c K + p interactions. A systematic comparison with the reaction K + p→pX for >| t p,p>| < 0.6 (GeV/ c ) 2 is made. The production properties of the Δ ++ (1232), of associated π + , π − and K 0 production and of the recoiling system X 0 are investigated in detail. The polarization of the Δ ++ and the energy dependence of the total K + π − cross sections, determined by a Chew-Low extrapolation, are presented and discussed.
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The inclusive reaction K + p → K 0 + X is studied at 5, 8.2 and 16 GeV/ c . The energy dependence and the shapes of inclusive spectra in the central region are found to be consistent with double-Regge expansion. With the values obtained for the parameters of the Regge expansion, prediction are made for the behaviour of the cross section at higher energies.
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We present results on the inclusive polarization of Λ hyperons produced in K + p interactions at 32 and 70 GeV/ c . A large positive Λ polarization is observed in the kaon fragmentation region. The polarization is energy independent, increases strongly with increasing x , but shows essentially no p T -dependence.
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Results are presented onK+p elastic scattering and on the reactionK+p→K+pπ+π− at 70 GeV/c. For the
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Cross sections and charged multiplicity distributions forK+p interactions at 70 GeV/c are presented and compared withK+p data at other energies. Comparisons are also made with available π+p,pp, andK−p data.
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Inclusive and semi-inclusive production of Λ and\(\bar \Lambda\) inK+p interactions is studied at an incident momentum of 70 GeV/c. Cross sections and single particle distributions are presented and compared with data at lower energies. Scaling is observed between 32 and 70 GeV/c in the Feynmanx variable in the target and the beam fragmentation regions for Λ and\(\bar \Lambda\) inclusive production respectively. An increase of Λ (\(\bar \Lambda\)) production is observed in the beam (target) fragmentation regions, whereas the data at 70 and 32 GeV/c are reasonably close in the central region. The dependence of the Λ(\(\bar \Lambda\)) polarization as a function ofx is measured and found to be in general agreement with the results at 32 GeV/c. The (Λ\(\bar \Lambda\)) pair production cross section increases significantly from 32 to 70 GeV/c. The Λ and\(\bar \Lambda\) production associated with an identified proton is also studied.
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Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incidentK+ beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π−'s and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π− cross section increases proportionally topLAB−1/4; positive particles show almost no energy dependence atx=0. Particle ratios π+/π− are studied as a function ofx andy* and a comparison with 70 GeV/cK−p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π± triggers at large |x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton.
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The inclusive production of neutral kaons in 70 GeV/ c K + p interactions is studied with the CERN BEBC bubble chamber. The (semi-)inclusive cross sections are interpreted in terms of the various strangeness channels leading to neutral kaon production. The invariant inclusive cross section for kaon production is studied as a function of p t 2 and the Feynman variable x . The latter distributions are considered both “raw” and corrected for the presence of K 0 's resulting from K ∗ decay. They are compared with the predictions expected from the Regge-Mueller formalism, the recombination model and fragmentation models.
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We report on a measurement of the ratio of the differential cross sections for W and Z boson production as a function of transverse momentum in proton-antiproton collisions at sqrt(s) = 1.8 TeV. This measurement uses data recorded by the D0 detector at the Fermilab Tevatron in 1994-1995. It represents the first investigation of a proposal that ratios between W and Z observables can be calculated reliably using perturbative QCD, even when the individual observables are not. Using the ratio of differential cross sections reduces both experimental and theoretical uncertainties, and can therefore provide smaller overall uncertainties in the measured mass and width of the W boson than current methods used at hadron colliders.
The measured W and Z0 cross sections used to compute the ratio.
The measured ratios of W+-/Z0 cross sections, corrected for the branching ratios BR(W-->e-nue)=0.1073+-0.0025 and BR(Z0-->E+E-)=0.033632+-0.000059 (PDG 2000). The error given is the total error, but note that the 4.3pct error in the luminosity cancels completely in the ratio.
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