Professor Chris Hays

Abstract:

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We define final states to be studied, and construct a rule that identifies a set of relevant variables for any particular final state. A new algorithm ("SLEUTH") searches for regions of excess in those variables and quantifies the significance of any detected excess. After demonstrating the sensitivity of the method, we apply it to the semi-inclusive channel eμX collected in 108 pb-1 of pp̄ collisions at √s=1.8 TeV at the DØ experiment during 1992-1996 at the Fermilab Tevatron. We find no evidence of new high pT physics in this sample. ©2000 The American Physical Society.

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.