A search for the standard model Higgs boson produced in association with a top-quark pair, t¯tH, is presented. The analysis uses 36.1  fb−1 of pp collision data at sqrt(s) = 13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H→b¯b decay mode. The selected events contain either one or two electrons or muons from the top-quark decays, and are then categorized according to the number of jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events, the latter being dominated by t¯t+jets production. For a Higgs boson mass of 125 GeV, the ratio of the measured t¯tH signal cross-section to the standard model expectation is found to be μ=0.84+0.64−0.61. A value of μ greater than 2.0 is excluded at 95% confidence level (C.L.) while the expected upper limit is μ<1.2 in the absence of a t¯tH signal.

Search for the standard model Higgs boson produced in association with top quarks and decaying into a b b pair in pp collisions at sqrt(s) =13 TeV with the ATLAS detector

G Chiodini;E Gorini;L Longo;A Mirto;M Reale;E Schioppa;S Spagnolo;A Ventura;
2018

Abstract

A search for the standard model Higgs boson produced in association with a top-quark pair, t¯tH, is presented. The analysis uses 36.1  fb−1 of pp collision data at sqrt(s) = 13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H→b¯b decay mode. The selected events contain either one or two electrons or muons from the top-quark decays, and are then categorized according to the number of jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events, the latter being dominated by t¯t+jets production. For a Higgs boson mass of 125 GeV, the ratio of the measured t¯tH signal cross-section to the standard model expectation is found to be μ=0.84+0.64−0.61. A value of μ greater than 2.0 is excluded at 95% confidence level (C.L.) while the expected upper limit is μ<1.2 in the absence of a t¯tH signal.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11587/425186
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