Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 8: Higgs Boson: Decay in Fermions 1

T 8.3: Vortrag

Montag, 21. März 2022, 16:45–17:00, T-H21

Improving the sensitivity of CP tests in VBF Higgs-boson production exploiting the H → τ_e τ_µ decay with neural networks for the reconstruction of the Higgs-boson four-momentum at the ATLAS experiment — •Alexandra Spitzer, Michael Böhler, and Markus Schumacher — Albert-Ludwigs-Universität Freiburg

Violation of CP invariance is one of the three Sakharov conditions needed to explain the observed baryon asymmetry in our universe. In the Standard Model CP violation is already introduced via the CKM matrix. However, its size is not sufficient to explain the amount of observed baryon asymmetry. The vector-boson fusion production of the Higgs particle allows to study its CP structure of the couplings to electroweak gauge bosons HVV.

CP invariance of HVV couplings is probed by investigating the mean value of the CP-odd Optimal Observable. Since the Higgs bosons’s four-momentum is required for calculating the Optimal Observable the resolution of the Optimal Observable is limited by the reconstruction quality of the Higgs boson’s four-momentum. It is investigated how neural networks improve the reconstruction quality of the four-momentum in comparison to the Missing Mass Calculator. The hyperparameters of four different neural networks were optimized by using a hyperparameter optimization software framework OPTUNA. The impact on determing the strength of CP violation in the H → τ_e τ_µ decay channel assuming L=139 fb⁻¹ of pp collisions at √s=13 TeV is presented.