Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb in pp collisions at √s =8TeV with the ATLAS detector

Barton, Adam and Beattie, Michael and Borissov, Guennadi and Bouhova-Thacker, Eva and Dearnaley, William and Fox, Harald and Grimm, Kathryn and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Maddocks, Harvey and Skinner, Malcolm and Smizanska, Maria and Walder, James and Wharton, Andy and Muenstermann, Daniel (2015) Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb in pp collisions at √s =8TeV with the ATLAS detector. European Physical Journal C: Particles and Fields, 75. ISSN 1434-6044

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Abstract

A search for the Standard Model Higgs boson produced in association with a top-quark pair, tt ¯ H , is presented. The analysis uses 20.3 fb−1 of pp collision data at s √ =8TeV , collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H→bb ¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by tt ¯ +jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible tt ¯ +bb ¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured tt ¯ H signal cross section to the Standard Model expectation is found to be μ=1.5±1.1 assuming a Higgs boson mass of 125GeV.

Item Type:
Journal Article
Journal or Publication Title:
European Physical Journal C: Particles and Fields
Additional Information:
© CERN for the benefit of the ATLAS collaboration 2015. This article is published with open access at Springerlink.com EPJC is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0 Date of acceptance not available
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2200/2201
Subjects:
ID Code:
75602
Deposited By:
Deposited On:
14 Sep 2015 08:24
Refereed?:
Yes
Published?:
Published
Last Modified:
31 May 2020 03:12