Search for Higgs boson in the WW* channel in ATLAS and drift time measurement in the liquid argon calorimeter in ATLAS

Abstract : A Higgs search is performed in the WW → lνlν channel using the full 2011 data at a center-of-mass energy of √s = 7 TeV and part of 2012 data at 8 TeV taken by the ATLAS experiment at the LHC. The corresponding integrated luminosity values are 4.7fb−1 and 5.8fb−1, respectively. The cut based analysis is performed and several data-driven methods for background estimation are introduced. The jet veto survival probability method for top background estimation in 0-jet bin is proposed and used in the Higgs search. Another data-driven method to correct the shape of the missing transverse energy distribution in the Drell-Yan process is also presented. In 2011, the standard model Higgs boson with the Higgs mass from 133 to 261 GeV is excluded at 95% CL, while the expected exclusion range is 127 − 234 GeV. In 2012, an excess of events over expected background is observed at mH = 125GeV. Combining the both samples, the minimum observed p0 value is 3 × 10−3, corresponding to 2.8 standard deviations. The fitted signal strength at mH = 125 GeV is μ = 1.4 ± 0.5. The expected p0 for a Higgs with mH = 125 GeV is 0.01, or 2.3 standard deviations. The exclusion limit for a Higgs in a fourth generation model is shown using part of the 2011 data sample, the mass range between 120GeV and 600GeV has been excluded at 95%CL. The study on the drift time in the liquid argon calorimeter in ALTAS is performed using all special data samples from cosmic muon, beam splash and beam collision data. The results show no significant non-uniformity on the cell gap width and a sagging effect due to gravity is observed.
Document type :
Theses
Other. Université Paris Sud - Paris XI; Institute of High Energy Physics (IHEP), 2012. English. <NNT : 2012PA112236>


https://tel.archives-ouvertes.fr/tel-00755876
Contributor : ABES STAR <>
Submitted on : Thursday, November 22, 2012 - 10:22:20 AM
Last modification on : Wednesday, November 28, 2012 - 11:04:55 AM

Identifiers

  • HAL Id : tel-00755876, version 1

Collections

STAR | LAL | CNRS

Citation

Xifeng Ruan. Search for Higgs boson in the WW* channel in ATLAS and drift time measurement in the liquid argon calorimeter in ATLAS. Other. Université Paris Sud - Paris XI; Institute of High Energy Physics (IHEP), 2012. English. <NNT : 2012PA112236>. <tel-00755876>

Export

Share

Metrics

Consultation de
la notice

266

Téléchargement du document

51