Precision Measurements of Higgs Hadronic Decay Modes at the FCC-ee

The expected precision at the FCC-ee on the product $\sigma\times\mathcal{B}(H\rightarrow b\bar{b}, c\bar{c},s\bar{s},gg)$ of Higgs boson production cross sections times branching ratios of hadronic decays is presented. This study provides the first comprehensive determination of all major hadronic Higgs decay modes in a combined fit at future $e^+ e^-$ colliders, using both Higgs-strahlung ($ZH$) and Vector boson fusion ($\nu\bar{\nu} H$) production processes, with a full treatment of interference effects in the $\nu\bar{\nu} jj$ final state. It assumes four identical IDEA detectors collecting $e^+e^-$ collisions at $\sqrt{s}=240$ and $365\,$GeV. The combination of all channels across both energies, with full covariance between production and decay modes, yields a production cross-section times branching-ratio precision at the percent to per-mil level for the dominant hadronic final states ($b\bar{b}, c\bar{c},gg$). These results provide a comprehensive input to the determination of Higgs coupling projections at the FCC-ee, and they establish for the first time sensitivity to the rare decay $H\rightarrow s\bar{s}$, demonstrating that FCC-ee has the potential to provide evidence of the strange-quark Yukawa coupling.