Professor Chris Hays

Abstract:

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb-1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction. © 2012 CERN.

Abstract:

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1 . Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction. © 2012 CERN.

Abstract:

A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 10fb -1 of integrated luminosity collected by the CDF experiment from proton-antiproton collisions at s=1.96TeV. To increase the sensitivity of the search, we employ a multivariate discriminant technique for the first time in this channel at CDF. No evidence of signal is observed, and upper limits are set on the cross section times branching ratio of the resonant state as a function of the Higgs boson mass. The limits are interpreted in the context of the standard model with an expected (observed) limit on the cross section times branching ratio of 9.9 (17.0) times the standard model prediction at the 95% credibility level for a Higgs boson mass of 125GeV/c 2. Moreover, a Higgs boson with suppressed couplings to fermions is excluded for masses below 114GeV/c 2 at the 95% credibility level. © 2012 Elsevier B.V.

Abstract:

A search for a heavy Standard Model Higgs boson decaying via H→ZZ→ℓ+ℓ-qq̄, where ℓ=e or μ, is presented. The search uses a data set of pp collisions at s=7TeV, corresponding to an integrated luminosity of 4.7fb-1 collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600GeV are derived. A Standard Model Higgs boson with a mass in the range 300GeV≤mH≤322GeV or 353GeV≤mH≤410GeV is excluded at 95% CL. The corresponding expected exclusion range is 351GeV≤mH≤404GeV at 95% CL. © 2012 CERN.

Abstract:

A search for a heavy Standard Model Higgs boson decaying via H→ZZ→ℓ+ℓ-qq̄, where ℓ=e or μ, is presented. The search uses a data set of pp collisions at s=7TeV, corresponding to an integrated luminosity of 4.7fb -1 collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600GeV are derived. A Standard Model Higgs boson with a mass in the range 300GeV≤m H ≤322GeV or 353GeV≤m H ≤410GeV is excluded at 95% CL. The corresponding expected exclusion range is 351GeV≤m H ≤404GeV at 95% CL. © 2012 CERN.