This thesis presents a search for Standard Model Higgs boson produced in association with top quark pairs, ttH. The analysis uses 13.2 fb-1 of pp collision data at √s = 13 TeV collected in 2015 and 2016 with the ATLAS detector at the LHC. The considered decay mode for the Higgs boson is H->bb and the single lepton decay channel (electron or muon) for the tt pair. The sensitivity of this channel is improved by an event categorisation according to the jet multiplicity and the number of jets containing a b-hadron decay. Multivariate techniques are used to distinguish the signa...

This thesis focuses on the search for the Standard Model Higgs boson produced in association with a pair of top quarks, ttH, using 20.3 fb-1 of pp collision data at sqrt{s} = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H -> bb decay mode and is performed in the single lepton channel, characterised by an isolated electron or muon, missing transverse energy and at least four jets. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities into nine analys...

The analysis described in this thesis is the search for the Higgs boson, decaying into bb pair, in the associated production with a vector boson, in the extreme Higgs boson transverse momentum region where the Higgs boson is reconstructed using the large-R jet technique. The use of the large-R jets allows to add a part of the phase space unexplored so far, which is particularly sensitive to possible new physics. The analysed data have been collected at LHC by the ATLAS detector between 2015 and 2018 at a centre-of-mass energy of √s = 13 TeV. The same dataset has been used to perform the differential pp → ZH and pp → WH cross-section measurements used to extract the information on the Higgs couplings and to put limits on Beyond the Standard Model effects. Furthermore the analysis has been re-used to perform a cross-section measurement of the diboson ZZ and WZ processes because the diboson and the Higgs processes have a similar topology. For the first time the ZZ(bb) and WZ(bb) cross-sections are measured at √s = 13 TeV and the observed cross-section measurements are consistent with the Standard Model predictions.

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A search for the Standard Model Higgs boson produced in association with a pair of top quarks (ttH) 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 → bb decay mode and is performed in the single lepton (electrons or muons) decay channel of the top quark pair. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities into nine different analysis regions. A matrix element method is deve...

This first open access volume of the handbook series contains articles on the standard model of particle physics, both from the theoretical and experimental perspective. It also covers related topics, such as heavy-ion physics, neutrino physics and searches for new physics beyond the standard model. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access