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T: Fachverband Teilchenphysik

T 47: Higgs 2 (ttH & tH production)

T 47.1: Vortrag

Dienstag, 5. März 2024, 16:00–16:15, Geb. 30.41: HS 2

ttH Multi-Lepton Analysis Results — •Stephen Eggebrecht, Steffen Korn, Arnulf Quadt, Baptiste Ravina, and Elizaveta Shabalina — II Physikalisches Institut, Georg August Universität Göttingen

The Higgs boson production in association with a top quark pair (ttH) plays a key role for studying the Yukawa coupling between the Higgs boson and the top quark. The coupling can be determined by measuring the cross-section of the ttH production process in various final states using the 140 fb⁻¹ Atlas dataset at √s=13 TeV. Multi-lepton final states are rare but pure since most backgrounds are significantly suppressed. An overview of ttH the multi-lepton analysis with a focus on the non-resonant ttH→4ℓ process is presented.
It is the multi-lepton final state with the lowest production rate and has contributions from Higgs decay modes like H→ WW^*, H→ττ, and H→ Z^*Z^*. The dominant background arises from ttZ, ZZ, and misidentified leptons from tt production. A multiclass dense neural network (DNN) is trained to separate signal events from these backgrounds and to define analysis regions. Additional fake lepton regions are defined to estimate the normalisation of the most important fake contributions. Preliminary fit results for the signal strength are presented for the 4ℓ channel. Furthermore, the combined performance of other multi-lepton final states is presented and discussed.

Keywords: ttH Multilepton; ATLAS