Prof Dr Armin Reichold

Abstract:

A search for gluinos and scalar quarks in a data sample of 84 pb ^-1 of pp̄ collisions at √s = 1.8 TeV was performed. The final state of large missing transverse energy and three or more jets was investigated. The data was compared with predictions of constrained supersymmetric models and gluinos masses below 195 GeV/c ², independent of the squark mass were excluded.

Abstract:

We present a measurement of the cross section and the first measurement of the heavy flavor content of associated direct photon + muon events produced in hadronic collisions. These measurements come from a sample of 1.8 TeV pp̄ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily due to the Compton scattering process cg→cγ, with the final-state charm quark producing a muon. The cross section for events with a photon transverse momentum between 12 and 40 GeV/c is measured to be 46.8±6.3±7.5 pb, which is two standard deviations below the most recent theoretical calculation. A significant fraction of the events in the sample contain a final-state bottom quark. The ratio of charm to bottom production is measured to be 2.4±1.2, in good agreement with QCD models.

Abstract:

The inclusive cross section for J/Ψ production times the branching ratio B(J/Ψ→μ ⁺ μ ^- ) has been measured in the forward pseudorapidity region: B×dσ[p ^- +p→J/Ψ(p T >10 GeV/c,2.1<|η|<2.6)+X]/dη = 192±9(stat) ±29(syst) pb. The results are based on 74.1±5.2 pb ^-1 of data collected by the CDF Collaboration at the Fermilab Tevatron Collider. The measurements extend earlier measurements of the D0 Collaboration to higher p T ^J/Ψ . In the kinematic range where the experiments partially overlap, these data are in good agreement with previous measurements.

Abstract:

We present measurements of the B⁺meson total cross section and differential cross section dσ/dpT. The measurements use a 98±4 pb^-1sample of pp̄ collisions at √s=1.8 TeV collected by the CDF detector. Charged B meson candidates are reconstructed through the decay B^±→J|ψ^±with J|ψ→µ⁺µ^-. The total cross section, measured in the central rapidity region |y|<1.0 for pT(B)>6.0 GeV/c, is 3.6±0.6(stat ⊕ syst) µb. The measured differential cross section is substantially larger than typical QCD predictions calculated to next-to-leading order.

Abstract:

We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at (Formula Presented)=630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio σ(630)/ σ(1800) 50.171±.024±.012 is in good agreement with next-to-leading order quantum chromodynamics.