D. L. Adams

Measurement of the inclusive differential cross section for Z bosons as a function of transverse momentum in p-bar p collisions at s√=1.8 TeV

We present a measurement of the differential cross section as a function of transverse momentum of the Z boson in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and the NNLO resummation prediction and extract values of the non-perturbative parameters for the resummed prediction from a fit to the differential cross section.

Measurement of the SMC muon beam polarisation using the asymmetry in the elastic scattering off polarised electrons

A muon beam polarimeter was built for the SMC experiment at the CERN SPS, for beam energies of 100 and 190 GeV. The beam polarisation is determined from the asymmetry in the elastic scattering off the polarised electrons of a ferromagnetic target whose magnetisation is periodically reversed. At muon energies of 100 and 190 GeV the measured polarisation is P-mu = -0.80 +/- 0.03 (stat.) +/- 0.02 (syst.) and P-mu = - 0.797 +/- 0.011 (stat.) +/- 0.012 (syst.), respectively. These results agree with measurements of the beam polarisation using a shape analysis of the decay positron energy spectrum

High-p(T) jets in p-barp collisions at s√=630 and 1800 GeV

Results are presented from analyses of jet data produced in pbarp collisions at sqrt{s} = 630 and 1800 GeV collected with the DO detector during the 1994-95 Fermilab Tevatron Collider run. We discuss details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at sqrt{s} = 630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at sqrt{s} = 630 and 1800 GeV are compared to next-to-leading-order QCD predictions. The order alpha_s^3 calculations are in good agreement with the data. We also use the data at sqrt{s} = 1800 GeV to rule out models of quark compositeness with a contact interaction scale less than 2.2 TeV at the 95% confidence level.

SIMULATION STUDIES OF TRACKING SYSTEMS AT VERY HIGH LUMINOSITY

Abstract Detailed computer simulation studies of a tracking detector originally designed for high luminosity operation at the Superconducting Super Collider have been carried out. Detector simulation and track reconstruction techniques appropriate to the extremely high charged particle rates corresponding to luminosities of up to 10 34 cm −2 s −1 are described. The detector performance is evaluated and compared to design requirements stemming from the physics goals of the SDC experiment. The results have implications for the design of tracking detectors at future high luminosity hadron colliders such as the Large Hadron Collider (LHC).

Measurement of the angular distribution of electrons from W⃗ eν decays observed in pp-bar collisions at s√=1.8 TeV

We present the first measurement of the electron angular distribution parameter α 2 in W→eν events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the DO detector during the 1994–1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1±α 1 cosθ ∗ +α 2 cos 2 θ ∗ ), where θ ∗ is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters α 1 and α 2 become functions of p T W , the W boson transverse momentum. This measurement provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W boson mass measurement.

Extraction of the width of the W boson from measurements of σ(pp-bar→W+X)×B(W⃗ eν) and σ(pp-bar→Z+X)×B(Z⃗ ee) and their ratio

We report on measurements of inclusive cross sections times branching fractions into electrons for W and Z bosons produced in ppbar collisions at sqrts=1.8 TeV.From an integrated luminosity of 84.5 inverse pb recorded in 1994--1995 using the D0 detector at the Fermilab Tevatron, we determine sigma(ppbar->W+X)B(W->e nu) = 2310 +- 10(stat) +- 50(syst) +- 100(lum) pb and sigma(ppbar->Z+X)B(Z->e e) = 221 +- 3(stat) +- 4(syst) +- 10(lum) pb. From these, we derive their Ratio R = 10.43 +- 0.15(stat) +- 0.20(syst) +- 0.10(NLO), B(W->e nu) = 0.1066 +- 0.0015(stat) +- 0.0021(syst) +- 0.0011(theory)+- 0.0011(NLO), and Gamma_W = 2.130 +- 0.030(stat) +- 0.041(syst) +- 0.022(theory) +- 0.021(NLO) GeV. We use the latter to set a 95% confidence level upper limit on the partial decay width of the W boson into non-standard model final states, Gamma_W^{inv}, of 0.168 GeV. Combining these results with those from the 1992--1993 data gives R = 10.54 +- 0.24, Gamma_W = 2.107 +- 0.054 GeV, and a 95% C.L. upper limit on Gamma_W^{inv} of 0.132 GeV. Using a sample with a luminosity of 505 inverse nb taken at sqrts=630 GeV, we measure sigma(ppbar->W+X)B(W->e nu) = 658 +- 67 pb.

Measurement of the inclusive differential cross section for Z bosons as a function of transverse momentum in p(bar sign)p collisions at {radical}( s )=1.8 TeV

We present a measurement of the differential cross section as a function of transverse momentum of the Z boson in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and the NNLO resummation prediction and extract values of the non-perturbative parameters for the resummed prediction from a fit to the differential cross section.

Limits on anomalous WW{gamma} and WWZ couplings from WW/WZ{yields}e{nu}jj production

Limits on anomalous WWγ and WWZ couplings are presented from a study of WW/WZ → eνjj events produced in pp collisions at √s=1.8 TeV. Results from the analysis of data collected using the DO detector during the 1993-1995 Tevatron collider run at Fermilab are combined with those of an earlier study from the 1992-1993 run. A fit to the transverse momentum spectrum of the W boson yields direct limits on anomalous WWγ and WWZ couplings. With the assumption that the WWγ and WWZ couplings are equal, we obtain -0.34<λ<0.36 (with Δκ=0) and -0.43<Δκ<0.59 (with λ=0) at the 95% confidence level for a form-factor scale Λ=2.0 TeV.

Search for bottom squarks in pp-bar collisions at s√=1.8 TeV

We report on a search for bottom squarks (b ∼ ) produced in pp‾ collisions at √s=1.8 TeV using the DO detector at Fermilab. Bottom squarks are assumed to be produced in pairs and to decay to the lightest supersymmetric particle (LSP) and a b quark with a branching fraction of 100%. The LSP is assumed to be the lightest neutralino and stable. We set limits on the production cross section as a function of b ∼ mass and LSP mass.

Measurement of W and Z boson production cross sections in pp-bar collisions at s√=1.8 TeV

DO has measured the inclusive production cross section of W and Z bosons in a sample of 13 pb