Recherche de production électrofaible supersymétrique dans des cascades de désintégration contenant un boson de Higgs avec le détecteur ATLAS au LHC

Abstract : Since the start of proton-proton collisions at LHC in 2009, the ATLAS and CMS experiments have recorded more than 25/fb of data each. The Higgs boson is akey prediction of the Standard Model of particle physics and its discovery in 2012 by the ATLAS and CMS experiments complete the Standard Model.The Standard Model, despite its excellent agreement with experiments at colliders, doesn't answer to many questions~: the nature of dark matter, dark energy... Furthermore, the instability of the Higgs mass under the effect of radiative corrections seems to indicate the existence of new physics at high energy.Among the theories beyond the Standard Model, supersymmetric models are excellent candidates to extend the Standard Model. During this thesis, between 2011 and 2014, I worked on the search of supersymmetric signals with the ATLAS experiment.First at L2C in Montpellier, where we have co-develloped a new version of SuSpect, a program designed to compute the MSSM mass spectrum.In the ATLAS groupe at CPPM in Marseille, I developped for the ATLAS collaboration a serie of tools based on artificial neural networks and decision trees to identify jets coming from b-quark hadronization. This tools have improved the discimination between different jets flavors for data analysis in ATLAS.Then, I analyzed the data collected by ATLAS in 2012 to obtain limits on the associated production charginos and neutralinos decaying via a W and a Higgs boson, resulting in a final state containing a charged lepton, two b-jets and missing transverse momentum
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Michaël Ughetto. Recherche de production électrofaible supersymétrique dans des cascades de désintégration contenant un boson de Higgs avec le détecteur ATLAS au LHC. Physique [physics]. Université Montpellier II - Sciences et Techniques du Languedoc, 2014. Français. ⟨NNT : 2014MON20090⟩. ⟨tel-01203771v1⟩

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