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Supersymmetric Exotic Decays of the 125 GeV Higgs Boson

We reveal a set of novel decay topologies for the 125 GeV Higgs boson in supersymmetry which are initiated by its decay into a pair of neutralinos, and discuss their collider search strategies. This category of exotic Higgs decays are characterized by the collider signature: visible objects + $\mbox{${\not\! E}_{\rm T}$}$, with $\mbox{${\not\! E}_{\rm T}$}$ dominantly arising from escaping dark matter particles. Their benchmark arises naturally in the Peccei-Quinn symmetry limit of the MSSM singlet-extensions, which is typified by the co-existence of three light particles: singlet-like scalar $h_1$ and pseudoscalar $a_1$, and singlino-like neutralino $χ_1$, all with masses of $\lesssim 10$ GeV, and the generically suppression of the exotic decays of the 125 GeV Higgs boson $h_2\to h_1 h_1$, $a_1a_1$ and $χ_1χ_1$, however. As an illustration, we study the decay topology: $h_2 \to χ_1 χ_2$, where the bino-like $χ_2$ decays to $h_1 χ_1$ or $a_1 χ_1$, and $h_1/a_1 \to f\bar f$, with $f\bar f = μ^+μ^-$, $b\bar b$. In the di-muon case ($m_{h_1/a_1} \sim 1$ GeV), a statistical sensitivity of $\frac{S}{\sqrt{B}} > 6 σ$ can be achieved easily at the 8 TeV LHC, assuming $\frac{σ(pp \rightarrow W h_2)}{σ(pp \rightarrow W h_{\rm SM})} {\rm Br}(h_2 \to μ^+μ^- χ_1 χ_1)=0.1$. In the $b\bar b$ case ($m_{h_1/a_1} \sim 45$ GeV), 600 fb$^{-1}$ data at the 14 TeV LHC can lead to a statistical sensitivity of $\frac{S}{\sqrt{B}} > 5 σ$, assuming $\frac{σ(pp \rightarrow Z h_2)}{σ(pp \rightarrow Z h_{\rm SM})} {\rm Br}(h_2 \to b\bar b χ_1 χ_1)=0.5$. These exotic decays open a new avenue for exploring new physics couplings with the 125 GeV Higgs boson at colliders.