Professor Chris Hays

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.

Abstract:

We investigate the potential for measuring the relative couplings of a low-mass Higgs boson at the Large Hadron Collider using WH, ZH, and tt̄H production, where the Higgs boson decays to tau-lepton pairs. With 100fb -1 of √s=14TeV pp collision data we find that these modes can improve sensitivity to coupling-ratio measurements of a Higgs boson with a mass of about 125GeV/c2. © 2012 American Physical Society.

Abstract:

Measurements are presented of the properties of high transverse momentum jets, produced in proton-proton collisions at a center-of-mass energy of √s=7TeV. The data correspond to an integrated luminosity of 35pb -1 and were collected with the ATLAS detector in 2010. Jet mass, width, eccentricity, planar flow and angularity are measured for jets reconstructed using the anti-kt algorithm with distance parameters R=0.6 and 1.0, with transverse momentum pT>300GeV and pseudorapidity |η|<2. The measurements are compared to the expectations of Monte Carlo generators that match leading-logarithmic parton showers to leading-order, or next-to-leading-order, matrix elements. The generators describe the general features of the jets, although discrepancies are observed in some distributions. © 2012 CERN, for the ATLAS Collaboration Published by the American Physical Society under the terms of the http://creativecommons. org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract:

Distributions sensitive to the underlying event are studied in events containing one or more charged-particle jets produced in pp collisions at √s=7TeV with the ATLAS detector at the Large Hadron Collider (LHC). These measurements reflect 800μb-1 of data taken during 2010. Jets are reconstructed using the anti-kt algorithm with radius parameter R varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of pTjet in regions transverse to and opposite the leading jet for 4GeV

More details from the publisher

More details