Document details

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

Author(s): Onofre, A. ; Castro, Nuno Filipe Silva Fernandes ; ATLAS Collaboration

Date: 2015

Persistent ID: http://hdl.handle.net/1822/39916

Origin: RepositóriUM - Universidade do Minho

Project/scholarship: info:eu-repo/grantAgreement/FCT/3599-PPCDT/143069/PT ;

Subject(s): Higgs physics; Top physics; Experimental results; Ciências Naturais::Ciências Físicas; Ciências Naturais::Ciências Físicas; Ciências Naturais::Ciências Físicas; Science & Technology; Science & Technology; Science & Technology


Description

A search for the Standard Model Higgs boson produced in association with a pair of top quarks, tt¯H, is presented. The analysis uses 20.3 fb−1 of pp collision data at s√ = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H to 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 125 GeV.

Document Type Journal article
Language English
Contributor(s) Onofre, A.; Castro, Nuno Filipe Silva Fernandes; ATLAS Collaboration
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