Bonn 2020 – scientific programme

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T: Fachverband Teilchenphysik

T 58: Higgs: associated production

T 58.3: Talk

Wednesday, April 1, 2020, 17:00–17:15, H-1.002

Measurement of the tt H production cross-section with H → bb in the boosted topology with the ATLAS detector — •Eftychia Tzovara, Peter Berta, Lucia Masetti, and Alexander Basan — Institute of Physics, JGU Mainz, Germany

Studying the coupling of the Higgs boson to the top quark (the heaviest particle in the SM) is of particular interest, since it could be very sensitive to effects of physics beyond the SM (BSM). The most favorable production mode for a direct measurement of the Higgs-top Yukawa coupling is the Higgs production in association with a pair of top quarks, tt H. The newly observed decay to two bottom quarks (H → bb ) has the largest branching fraction of about 58%. This analysis aims at events in which one of the top quarks decays semi-leptonically, producing an electron or a muon. In the single-lepton channel, the so-called boosted topology, targets events containing a Higgs boson produced at high transverse momentum.

Due to the highly complex final state and the large Standard Model backgrounds, measuring the signal strength in this process is very challenging. The ultimate goal is to precisely estimate the amount of background events in order to maximise the significance of the measurement. For this purpose, multivariate techniques are used to discriminate between signal and background events, in particular from tt + jets production. In this talk, the challenges of this decay channel and the suppression of the background processes will be discussed. Finally, the measurement of the tt H(bb ) cross-section, using the full LHC run-2 data collected by the ATLAS detector, will be presented.