Hamburg 2016 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 25: Higgs-Boson (assoziierte Produktion) II

T 25.2: Vortrag

Montag, 29. Februar 2016, 17:00–17:15, VMP5 HS B1

Search for the production of the Higgs boson in association with a pair of top quarks in the 3 leptons final state at 13 TeV in ATLAS — •Nello Bruscino, Markus Cristinziani, Mazuza Ghneimat, Sebastian Heer, Vadim Kostyukhin, Liza Mijović, Andrea Sciandra, and Kaven Yau Wong — Physikalisches Institut, Universität Bonn

The observation of the Higgs boson in association with a top-quark pair will open a window to the direct study of the Yukawa couplings of the top quark, which is the fermion expected to couple most strongly to the Higgs boson. Thanks to the LHC upgrade to 13 TeV ttH events are produced with a significantly higher cross section than at 8 TeV. Final states with high light leptons multiplicity, targeting the H→ WW^*/ττ/ ZZ^* decay channels, can consequently be exploited to research the presence of a Standard Model (SM) Higgs boson.
The 3 leptons analysis includes exactly 3 light leptons with total charge equal to ± 1. To suppress the tt+jets and ttV backgrounds, selected events are required to include either at least 4 jets of which at least one must be b-tagged, or exactly 3 jets of which at least 2 b-tagged. The ttH to 3 light leptons final state is dominated by the H→ WW^* decay: either 2 leptons originate from the Higgs decay and an additional one from top, or 1 lepton from Higgs and 2 leptons from tops. Further 3 leptons configurations are thinkable, making it harder to pursue this final state. A Pseudo Matrix Element (P.M.E.) approach is developed and used in order to identify signal-like events by partially reconstructing resonances and recognizing peculiar kinematic variables.