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T: Fachverband Teilchenphysik

T 82: Higgs, Di-Higgs II

T 82.4: Talk

Wednesday, March 22, 2023, 18:15–18:30, HSZ/0105

Search for a light CP-odd Higgs boson with ATLAS — •Tom Kreße, Arno Straessner, Manuel Gutsche, Hannah Jacobi, and Christian Schmidt — IKTP, Dresden, Germany

Even though theoretical predictions of the SM are corresponding to experimental results to an incredible degree, there are still some phenomena unexplained, for example the deviation of the measured anomalous magnetic moment, g-2, of the muon from SM calculations. This deviation could be explained by the flavor-aligned two-Higgs-doublet model. The introduction of a second Higgs doublet leads to four additional Higgs bosons, one of which being CP-odd and electrically neutral. The muon g-2 deviation is best explained with a light CP-odd Higgs boson which couples nearly exclusively to top quarks and tau leptons.

This talk presents the search of such a light CP-odd Higgs boson produced via gluon fusion. The decay into two tau leptons is analyzed by requiring one electron and one muon in the final state. The search is carried out in the mass range between 20 GeV and 110 GeV. It is based on 139 fb-1 of data collected by the ATLAS experiment at 13 TeV center-of-mass energy.

The analysis strategy as well as the various validation regions to check the background estimation are presented. An overview over the most relevant systematic uncertainties is given. Even though the analysis is still blinded, expected limits for the production cross-section and model-dependent coupling parameters can be calculated and the fits can be checked for consistency. An outline for the further steps towards the unblinding and the publication of the analysis is given.