Erlangen 2026 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 89: Higgs Physics IX

T 89.1: Vortrag

Freitag, 20. März 2026, 09:00–09:15, KH 00.014

Test of CP invariance in Higgs boson production via vector boson fusion at the HL-LHC exploiting the H→ττ decay mode — •Daniel Bahner, Lorenzo Rossini, and Markus Schumacher — Albert-Ludwigs-Universität, Freiburg, Deutschland

The observed baryon asymmetry of the Universe can be accounted for only if the three Sakharov conditions are satisfied, one of which is the violation of CP invariance. However, the amount of CP violation predicted by the Standard Model is insufficient to generate the observed asymmetry through electroweak baryogenesis. Precision measurements of the Higgs boson therefore offer a promising avenue to search for additional sources of CP violation. In particular, the vector-boson fusion (VBF) production mode provides sensitivity to potential CP-violating contributions in the HVV coupling.

This talk focuses on VBF Higgs boson production followed by its decay into a pair of tau leptons. ATLAS published an analysis in 2025 that set the most stringent limits to date on the CP-violating coupling parameters in the HVV vertex using data collected from 2015 to 2018 corresponding to an integrated luminosity of L_int = 140 fb⁻¹ . Building on that work, the extrapolation of the analysis to the High-Luminosity LHC dataset, corresponding to L_int = 3000 fb⁻¹ at √s = 14 TeV , will be discussed. The study performs a profile-likelihood fit to the CP-odd optimal observable to test CP invariance and to constrain the magnitude of possible new CP-violating interactions. Results from the published analysis, the extrapolation methodology, and the expected sensitivity to the coupling parameter at the HL-LHC will be presented.

Keywords: CP Violation; VBF; Vector Boson Fusion; Tau Leptons