Speaker
Description
We study the prospects for probing exotic Higgs decays at a future muon collider in a minimal extension of the Standard Model with a light singlet scalar $S$. We focus on the process $h \to SS$ and consider two representative final states, $4b$ and $2b2\mu$. Our analysis is performed for muon collider benchmark scenarios at $\sqrt{s}=3~\mathrm{TeV}$ with $1~\mathrm{ab}^{-1}$ and $\sqrt{s}=10~\mathrm{TeV}$ with $10~\mathrm{ab}^{-1}$. Signal and background events are simulated using a full analysis chain, and machine-learning techniques are employed to improve background rejection and reduce jet combinatorics ambiguities. We find that the $4b$ channel can probe branching fractions $\mathrm{BR}(h \to SS \to 4b)$ at the level of $\mathcal{O}(10^{-2})$ at $3~\mathrm{TeV}$ and $\mathcal{O}(10^{-3})$ at $10~\mathrm{TeV}$, substantially extending the projected reach of the HL-LHC. The $2b2\mu$ final state benefits from a clean dimuon resonance and can reach sensitivity to $\mathrm{BR}(h \to SS \to 2b2\mu)$ at the $10^{-5}$ level at a $10~\mathrm{TeV}$ muon collider. These results demonstrate the strong potential of a high-energy muon collider for exploring exotic Higgs decays and light scalar sectors beyond the Standard Model.