Probing the charm Yukawa coupling: H→cc at CMS

by Sebastian Wuchterl (CERN)

Monday 20 Oct 2025, 11:00 → 12:00 Europe/Zurich

BSP 626 (EPFL)

Since the discovery of the Higgs boson (H) by the ATLAS and CMS
experiments, the observed interactions with gauge bosons and third-generation fermions, as well as all its measured properties, align with the standard model predictions. Following the first evidence of Higgs boson decays to muons, i.e., second-generation leptons, a next important milestone is to observe its couplings to second-generation quarks.

The most promising avenue is searching for Higgs boson decays to a charm quark-antiquark pair, H->cc, which provides direct access to the charm quark Yukawa coupling.

This seminar presents a new search for Higgs boson decays to a charm–anticharm quark pair (H→cc) in events produced alongside a top quark pair (ttH), utilizing the full LHC Run 2 dataset collected by the CMS. Advanced machine learning techniques are applied to improve jet flavor tagging and event classification.

A simultaneous fit extracts the signal strengths for ttH and ttZ production with charm and bottom final states. Combining these results with previous searches in associated vector boson production sets the most stringent constraints yet on the charm Yukawa coupling to date.

SW_Hcc_EPFL.pdf