Dark Matter Induced Nucleon Decay Through the Neutron Portal

The neutron portal operator provides a theoretically motivated connection between the visible and dark sectors and features in several well-studied asymmetric dark matter models. This operator leads to dark matter induced nucleon decays that mimic the experimental signature of “ordinary” nucleon decays. In this work, we reinterpret Super-Kamiokande nucleon decay searches for $n\to {\pi }^0\nu$ and $p\to {\pi }^{+}\nu$ to constrain dark matter induced nucleon decays. For GeV-scale dark matter, we obtain lower bounds of $\mathcal{O}(1\mathrm{T}\mathrm{e}\mathrm{V})$ on the scale of the effective neutron portal operator. We also discuss the prospects for future searches at Hyper-Kamiokande and highlight the importance of a dedicated experimental analysis with reduced systematic uncertainties.