Dark-Matter-Induced Nucleon Decay Signals in Mesogenesis

We introduce and study the first class of signals that can probe the dark matter in mesogenesis, which will be observable at current and upcoming large volume neutrino experiments. The well-motivated mesogenesis scenario for generating the observed matter-antimatter asymmetry necessarily has dark matter charged under the baryon number. Interactions of these particles with nuclei can induce nucleon decay with kinematics differing from spontaneous nucleon decay. We calculate the rate for this process and develop a simulation of the signal that includes important distortions due to nuclear effects. We estimate the sensitivity of DUNE, Super-Kamiokande, Hyper-Kamiokande, and JUNO to this striking signal.

Figure 1

Induced proton decay to a pion through ${\mathcal{O}}_{u,dd}$.

Figure 2

Parameter space and kinetic energy contours for the eight different DM IND processes arising in mesogenesis. Colored regions are ruled out by kinematics, Eq. (2), or mechanism considerations, Eq. (5). Solid lines correspond to kinetic energy for scattering off protons $N=p$ and the dashed off nucleons $N=n$. In each panel, we indicate the location of the representative BMs: 1, 2, $3p$, $4p$ for pions and 1, 2, $3k$, $4k$ for kaons as summarized in Table 2.

Figure 3

Kinetic energy distributions for a sample BM model at Hyper-Kamiokande and JUNO. Super-Kamiokande is simply a rescaling of the rate at Hyper-Kamiokande by a factor of 16. Dashed lines indicate the unsmeared energy, Eq. (3). Green lines indicate, where relevant, the assumed threshold for the detector to see the meson. The Hyper-Kamiokande and JUNO signals have a monoenergetic spike corresponding to scattering off hydrogen, while the smeared distribution corresponds to scatterings off oxygen. The couplings are chosen at our estimated threshold of sensitivity.

Figure 4

Kinetic energy distributions for sample BM models at DUNE for the kaon channel with the conventions outlined in Fig. 3.