Nackenhorst, OlafOlafNackenhorst2019-07-092019-07-092013https://resolver.sub.uni-goettingen.de/purl?gro-2/58269A search for a Higgs boson produced in association with a pair of top quarks and decaying into apair of b quarks is presented. The analysis uses an integrated luminosity of 4.7 fb−1 of pp collisions at a center-of-mass energy of = 7 TeV collected in 2011 with the ATLAS detector at the LHC. The search is focused on the semileptonic decay of the tbar t system and combines nine different topologies given by the jet and b-tagged jet multiplicities of the event. A kinematic reconstruction of the Higgs boson mass is performed in the signal enhanced region, which becomes the primary discriminant variable between signal and background. Background-dominated samples are exploited to constrain the leading systematic uncertainties affecting the background prediction. No significant excess of events above the background expectation is observed. For a Higgs boson with a mass of 125 GeV, an observed (expected) 95% confidence upper limit of 13.1 (10.5) times the Standard Model cross section is obtained.enCC BY 3.0http://creativecommons.org/licenses/by/3.0/journal_article10.1088/1742-6596/452/1/0120572022-02-23https://resolver.sub.uni-goettingen.de/purl?gs-1/11413