# A sub-GeV dark matter model

## TL;DR

This paper introduces a new gauge symmetry extension to the Standard Model, addressing fermion mass hierarchies and proposing a sub-GeV dark matter candidate with viable detection prospects.

## Contribution

It presents a novel $U(1)_{T3R}$ gauge extension that explains fermion hierarchy and predicts a light dark matter particle with specific interaction features.

## Key findings

- Dark matter mass in 1-100 MeV range.
- Model satisfies current experimental constraints.
- Predicts both elastic and inelastic DM-nucleon scattering.

## Abstract

We propose an extension of the Standard Model gauge symmetry by the gauge group $U(1)_{T3R}$ in order to address the Yukawa coupling hierarchy between the third generation fermions and the first two generation fermions of the SM. We assume that only the right-handed fermions of the first two generations are charged under the $U(1)_{T3R}$. In addition to the new dark gauge boson, we have a dark scalar particle whose vacuum expectation value (vev) breaks the $U(1)_{T3R}$ symmetry down to $Z_2$ symmetry and also explains the hierarchy problem. A vev of $\cal O$(GeV) is required to explain the mass parameters of the light flavor sector naturally. The dark matter (DM) particle arising from the model naturally has mass in the $\mathcal {O}$(1-100) MeV range. The model satisfies all the current constraints. We discuss the various prospects of the direct detection of the dark matter. We get both elastic and inelastic spin independent DM-nucleon scattering. The dark matter obtains the correct thermal relic density by annihilation.