Sterile Neutrino Portal Dark Matter from Semi-Production

TL;DR

This paper explores a novel sterile neutrino portal dark matter model with a $Z_3$ symmetry, analyzing new production channels and their cosmological implications.

Contribution

It introduces a $Z_3$ symmetric dark sector with unique interactions, detailing new production mechanisms and decay channels for sterile neutrino portal dark matter.

Findings

Dark matter candidate $ ext{fermion } ext{ extchi}$ can be produced via semi-production processes.

The decay channel $ extphi o ext{ extchi} ext{ extchi}$ can dominate when $m_ extphi > 2m_ extchi$.

The model's phenomenology and cosmological effects are analyzed within the $Z_3$ symmetry framework.

Abstract

In this paper, we study the feeble sterile neutrino portal dark matter under the $Z_3$ symmetry. The dark sector consists of one fermion singlet $\chi$ and one scalar singlet $\chi$, which transforms as $\chi\to e^{i2\pi/3}\chi, \phi\to e^{i2\pi/3}\phi$ under the $Z_3$ symmetry. Regarding fermion singlet $\chi$ as the dark matter candidate, the new interaction terms $y_\chi \phi \bar{\chi^c}\chi$ and $\mu\phi^3/2$ could induce various new production channels. For instance, when $m_\phi>2m_\chi$, the pair decay $\phi\to\chi\chi$ could be the dominant channel, rather than the delayed decay $\phi\to\chi\nu$. Another appealing scenario is when the dark sector is initially produced through the scattering process as $NN\to\chi\chi, NN\to\phi\phi,h\nu\to\chi\phi$, then the semi-production processes $N \chi\to\phi\phi, N\phi\to\phi\chi, N\chi\to\chi\chi$ could lead to the exponential growth of dark sector abundances. The phenomenology of sterile neutrino and the cosmological impact of the dark scalar are also considered in the $Z_3$ symmetric model.