Professor Chris Hays

Abstract:

The result of a search for gaugino pair production with a trilepton signature is reinterpreted in the framework of minimal supergravity (MSUGRA) with R-parity violation via leptonic λ Yukawa couplings. The search used 95 pb-1 of pp̄ collisions at √s=1.8 TeV recorded by the DØ detector at the Fermilab Tevatron. A large domain of the MSUGRA parameter space is excluded for λ121, λ122≥10-4. ©2000 The American Physical Society.

Abstract:

Limits on anomalous WWγ and WWZ couplings are presented from a study of WW/WZ→e vjj events produced in pp̄ collisions at √s=1.8 TeV. Results from the analysis of data collected using the DØ 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. ©2000 The American Physical Society.

Abstract:

Limits on anomalous WWγ and WWZ couplings are presented from a study of WW/WZ→e vjj events produced in pp̄ collisions at √s=1.8 TeV. Results from the analysis of data collected using the DØ 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. ©2000 The American Physical Society.

Abstract:

We present measurements of the bb̄ production cross section and angular correlations using the DO detector at the Fermilab Tevatron pp̄ Collider operating at √s = 1.8 TeV. The b quark production cross section for |y(b)| < 1.0 and p(T)/b > 6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and b̄ quarks, measured from the azimuthal opening angle between their decay muons, also agree in shape with the next-to-leading order QCD prediction. (C) 2000 Elsevier Science B.V.

Abstract:

Events in p̄p collisions at √s= 1.8 TeV with total transverse energy exceeding 500 GeV are used to set limits on quark substructure. The data are consistent with next-to-leading order QCD calculations. We set a lower limit of 2.0 TeV at 95% confidence on the energy scale ΛLL for compositeness in quarks, assuming a model with a left-left isoscalar contact interaction term. The limits on ΛLL are found to be insensitive to the sign of the interference term in the Lagrangian. ©2000 The American Physical Society.