Nucleon-decay-like signatures of hylogenesis

We consider nucleon-decay-like signatures of hylogenesis, a variant of the antibaryonic dark matter model. For the interaction between visible and dark matter sectors through the neutron portal, we calculate the rates of dark matter scatterings off a neutron which mimic neutron-decay processes $n\to \nu \gamma$ and $n\to \nu e^{+}{e}^{-}$ with richer kinematics. We obtain bounds on the model parameters from nonobservation of the neutron decays by applying the kinematical cuts adopted in the experimental analyses. The bounds are generally (much) weaker than those coming from the recently performed study of events with a single jet of high transverse momentum and missing energy observed at the LHC. Then we suggest several new nucleon-decay-like processes with two mesons in the final state and estimate (accounting for the LHC constraints) the lower limits on the nucleon lifetime with respect to these channels. The obtained values appear to be promising for probing the antibaryonic dark matter at future underground experiments like HyperK and DUNE.

Figure 1

Contours (thin lines) of constant lifetime (in years) of a neutron with respect to the processes $\mathrm{\Psi }n\to \mathrm{\Phi }\gamma$ and $\mathrm{\Phi }n\to \mathrm{\Psi }\gamma$, assuming equal number densities of the two dark matter components and parameters $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$. Present experimental bounds are applicable in the violet (light grey) regions on the plot. Thick lines in these regions show the limits on the quantity ${({\mathrm{\Lambda }}^2{M}_X/y)}^{1/3}$ in GeV.

Figure 2

Contours (thin lines) of constant lifetime (in years) of a neutron with respect to the process $\mathrm{\Psi }(\mathrm{\Phi })n\to \mathrm{\Phi }(\mathrm{\Psi })e^{+}{e}^{-}$; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$. Present experimental bounds are applicable in the violet (light grey) region on the plot. Thick lines in this region show the limits on the quantity ${({\mathrm{\Lambda }}^2{M}_X/y)}^{1/3}$.

Figure 3

Lifetime of a neutron with respect to IND $n\to e^{+}{e}^{-}$ for $\eta =100$ and $\eta =0.01$; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$. The current limits are applied in shaded regions.

Figure 4

Lifetime of a neutron with respect to the processes $\mathrm{\Phi }+n\to \mathrm{\Psi }+\gamma$ (for $\eta =100$) and $\mathrm{\Psi }+n\to \mathrm{\Phi }+\gamma$ (for $\eta =0.01$); we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 5

The Feynman diagrams for the process $\mathrm{\Psi }+p\to \mathrm{\Phi }+{\overline{K}}^0{K}^{+}$.

Figure 6

The Feynman diagrams for the process $\mathrm{\Psi }+p\to \mathrm{\Phi }+{\pi }^{+}{\pi }^0$.

Figure 7

Contours of constant lifetime (in years) of the nucleon in the symmetric case with respect to IND process with ${\pi }^{+}{\pi }^0$ in the final state; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 8

The Feynman diagrams for the process $\mathrm{\Psi }+n\to \mathrm{\Phi }+{\pi }^{+}{\pi }^{-}$ .

Figure 9

The Feynman diagrams for the process $\mathrm{\Psi }+p\to \mathrm{\Phi }+{\pi }^{+}\eta$ .

Figure 10

Contours of the constant lifetime (in years) of the nucleon in the symmetric case with respect to IND with ${\pi }^{+}\eta$ in the final state; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 11

Contours of the constant lifetime (in years) of the nucleon in the symmetric case with respect to IND with ${\pi }^0\eta$ in the final state; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 12

Contours of the constant lifetime (in years) of the nucleon in the symmetric case with respect to IND process with ${\pi }^0{\pi }^0$ in the final state; we set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 13

Contours of constant lifetime (in years) of the nucleon in the asymmetric case, $\eta =100$, with respect to the two-meson processes: a) ${\overline{K}}^0{K}^{+}$; b) $\eta \eta$; c) ${\pi }^0\eta$; d) ${\pi }^{+}\eta$; e) ${\pi }^0{\pi }^0$; g) ${\pi }^{+}{\pi }^0$. Numbers for other processes with kaons are similar to a) while for process with ${\pi }^{+}{\pi }^{-}$are similar to g). We set $\mathrm{\Lambda }=M_X=1\mathrm{TeV}$ and $y=1$.

Figure 14

Contours of constant lifetime (in years) of the nucleon in the asymmetric case, $\eta =0.01$, with respect to the two-meson processes. Other notations are the same as in Fig. 13.