Abstract
Dark matter that participates in baryon-number violating interactions can annihilate with baryons if the dark matter particle is not protected under discrete symmetries. In this paper we investigate the dark matter - baryon annihilation in color-triplet extensions of the Standard Model, in which a fermionic dark matter can be kinematically stable within a small mass range near the proton mass. We demonstrate that the DM's annihilation with nucleons can be probed to stringent limits at large-volume water Cherenkov detectors like the Super-Kamionkonde experiment, with the mediator scale $m_\Phi$ constrained up to $10^{7}$ GeV. In case of a Majorana light dark matter, this constraint is weaker yet close in magnitude to that from neutron-antineutron oscillation. In the Dirac DM case, the dark matter- nucleon annihilation gives much stronger bounds than that from the uncertainties of the neutron decay lifetime. In a limited range of the DM mass above $m_p+m_e$, the DM-nucleon annihilation bound can be higher than the requirement from the DM's stability in the Universe. Given the strong limits from Super-Kamionkonde, we find it below the current experimental capabilities to indirectly detecting the dark matter- nucleon annihilation signal in diffuse Galactic gamma rays and neutron star heating.
Highlights
The existence of dark matter (DM) is widely supported by astrophysical [1,2] and cosmological [3,4] observations
In this paper we investigate the dark matter– baryon annihilation in color-triplet extensions of the standard model, in which a fermionic dark matter can become kinematically stable within a small mass range near the proton mass
In this paper we investigated the dark matter annihilate with baryons through baryon number violating extensions to the standard model
Summary
The existence of dark matter (DM) is widely supported by astrophysical [1,2] and cosmological [3,4] observations. An interesting aspect of such a light dark matter is that it can stay kinematically stable [5,8,9] within a narrow mass range close to the proton’s mass, where the protection of a discrete symmetry may not be needed: a small dark matter–proton mass difference less than the electron mass can avoid the weak decay of dark matter, and prevent the proton decay via the dark matter’s mixing with the neutron through the baryon number violating interaction.
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