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T: Fachverband Teilchenphysik

T 82: Higgs, Di-Higgs II

T 82.6: Talk

Wednesday, March 22, 2023, 18:45–19:00, HSZ/0105

Top background estimation in the search for a light CP-odd Higgs boson with ATLAS — •Christian Schmidt, Tom Kreße, Manuel Gutsche, Hannah Jacobi, and Arno Straessner — IKTP, Dresden, Germany

Even though predictions of the Standard Model correspond to experimental results to an incredible degree, there are some deviations, for example between the measured anomalous magnetic moment g-2 of the muon and SM calculations.

To resolve this problem expansions to the Standard Model, like the 2HDM, are proposed. This theory predicts two Higgs doublets and therefore a total of five Higgs bosons with one of them being the CP-odd and neutral A boson. Assuming the A boson has a light mass and couples strongly to leptons and top-quarks, the model can predict a value for g-2 compatible with the measured one.

This talk describes the experimental search for such a light CP-odd Higgs boson with a mass of 20 to 110 GeV. The analysis aims to detect this A-boson by its production from gluon fusion and its decay via two tau-leptons into a final state containing one electron and one muon.

To be able to spot the extra events caused by A-boson decay, it is necessary to know the rate of background events very precisely. Background events have the same detector signature as signal events, but are caused by Standard Model processes. Their rate can be estimated by the Monte Carlo method. The talk focuses on the background caused by the decay of top quark-antiquark pairs, and the associated uncertainties due to approximations in the Monte Carlo generator.