Erlangen 2026 – scientific programme
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T: Fachverband Teilchenphysik
T 89: Higgs Physics IX
T 89.3: Talk
Friday, March 20, 2026, 09:30–09:45, KH 00.014
Probing CP invariance in the decay H→ττ at a future e+e− Linear Collider — •Lea Kuttler, Michael Böhler, and Markus Schumacher — Institute of Physics, Albert-Ludwigs-University Freiburg, Freiburg, Germany
Sources of CP violation (CPV) beyond the Standard Model (SM) are required to explain the baryon asymmetry observed in our universe (BAU). The Yukawa coupling of the Higgs boson to the tau lepton may deliver a sufficient source of CPV, which allows explaining the observed size of the BAU.
This analysis investigates the CP-nature of the Hττ Yukawa coupling, considering ee → ZH events at an e+ e− linear collider, operating at √s = 250 GeV, assuming an integrated luminosity of 2 ab−1 and e−/e+ beam polarizations of 80%/30%. Events are simulated for the International Large Detector concept.
In H → ττ decays, the strength of CP violation can be parametrized by a single mixing angle ψτ. Two observables sensitive to ψτ are the azimuthal angle difference Δ φ between the tau lepton polarimeter vectors and the matrix-element-based optimal observable OO.
This contribution demonstrates the use of these observables to constrain ψτ at a future e+ e− linear collider using the decay modes τ→ρν and πν and compares their sensitivity. In this context, methods for fully reconstructing the tau leptons and for identifying hadronic tau decays are presented.
Keywords: CP-violation; Higgs->tau tau; Future e⁺e⁻ linear collider