Speaker
Description
The precise measurement of the Higgs boson coupling to other standard model (SM) particles allows for up to 30\% of the Higgs boson width to originate from beyond the SM (BSM) decays. In the SM, the Higgs boson decays to invisible final states through the $H\rightarrow ZZ \rightarrow 4\nu$ process with a branching fraction of $(\mathcal{O})10^{-3}$ . This rate can be significantly enhanced if the Higgs boson decays into a pair of weakly interacting massive particles (WIMP), which may explain the nature of dark matter. The FCC-ee is a Higgs factory, with over one million Higgs bosons produced at $\sqrt{s} \sim$ 240 and 365 GeV, which can give access to Higgs decays with branching ratios of a fraction of a per mil. Preliminary studies of the invisible decay channel at FCC-ee are performed in the $Z\rightarrow H$ ($Z \rightarrow ff, H \rightarrow $ invisible) channel. We estimate the sensitivity at $\sqrt(s)=240$ GeV using full CLD simulation for the signal and smaller backgrounds. This is compared to earlier results using fast simulation. In addition, we propose to use the $H\rightarrow $ invisible channel to study the detector performance at the FCC-ee.
