Master Thesis

PUBDB-2026-01008

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Search for CP violation in the tau Yukawa coupling with the CMS Run 3 data

Witt, M. (Corresponding author)Extern* ; Gallo-Voss, E. (Thesis advisor)DESY*

2026

Abstract: This thesis presents a precision measurement of the CP properties of the Higgs tau Yukawa coupling, focusing on the H → τ τ → μa3pr 1 +3ν decay channel with ggF and VBF production.The study uses proton–proton collisions data recorded by CMS in 2022 and 2023 at √s = 13.6TeV, corresponding to an integrated luminosity of 62.4 fb−1. The CP-mixing angle αHττ is determined via the coplanarity angle ϕCP . In the μa3pr 1 channel, IP and ⃗hPV methods are combined for the first time, potentially allowing a twofold improvement in sensitivity compared to the DP method used for hadronic tau decays in Run 2. The tau momenta are reconstructed stepwise, first correcting the amplitudes with the fastMTT di-tau mass reconstruction algorithm and subsequently the angles with a Global Event Fit (GEF). The expected sensitivity to αHττ is improved within the μa3pr 1 channel from 0.41 σ to 0.49 σ, corresponding to a 20% enhancement. The result from this channel will contribute to a combined analysis across all di-tau channels.

Note: Masterarbeit, University of Hamburg, 2026

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Contributing Institute(s):

1. LHC/CMS Experiment (CMS)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)

Experiment(s):

1. LHC: CMS

Appears in the scientific report 2026

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