Göttingen 2025 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 68: Higgs Physics VIII (CP)

T 68.1: Vortrag

Donnerstag, 3. April 2025, 16:15–16:30, ZHG105

Measurement of CP-properties of the top Yukawa coupling via ttH and tH production in the H→γγ decay channel at CMS — Johannes Erdmann and •Florian Mausolf — III. Physikalisches Institut A, RWTH Aachen University

After the observation of the Higgs boson at the LHC and with continuing accumulation of data, its properties can be determined with increasing precision. Among these properties, the strength of the couplings to fermions and the CP-properties of its interactions are of particular importance. The top-quark Yukawa coupling, the Higgs boson’s strongest interaction with fermions, plays a central role in theory and experiment. While a purely CP-odd structure has been experimentally excluded, the possibility of a significant CP-odd admixture remains consistent with current LHC constraints. A CP-odd component would influence both the cross-sections and kinematics of top-quark-associated Higgs production processes, ttH and tH. For example, the tH cross-section would increase significantly with the inclusion of a sizeable CP-odd component.

This talk presents the strategy and ongoing developments for a measurement of ttH and tH production cross sections and the CP-properties using events where the Higgs boson decays into two photons. A particular emphasis is placed on a novel approach to separate ttH and tH production processes, enabling individual ttH and tH cross-section measurements without relying on strong assumptions about CP-even and CP-odd coupling modifiers.

Keywords: Higgs boson; Top Yukawa coupling; CP-properties; Diphoton decay