# A model with isospin doublet $U(1)_D$ gauge symmetry

## TL;DR

This paper introduces a novel gauge symmetry extension with an isospin doublet $U(1)_D$, analyzing its implications for anomaly cancellation, Higgs charge constraints, and dark matter relic density.

## Contribution

It proposes a new $U(1)_D$ gauge symmetry model with anomaly cancellation via extra fermions and explores its impact on dark matter and Higgs physics.

## Key findings

- Stringent constraints on $U(1)_D$ breaking scale from Higgs charge
- Viable parameter space for Majorana dark matter consistent with observations
- Global analysis identifies conditions fitting experimental data

## Abstract

We propose a model with an extra isospin doublet $U(1)_D$ gauge symmetry, in which we introduce several extra fermions with odd parity under a discrete $Z_2$ symmetry in order to cancel the gauge anomalies out. A remarkable issue is that we impose nonzero $U(1)_D$ charge to the standard model Higgs, and it gives the most stringent constraint to the vacuum expectation value of a scalar field breaking the $U(1)_D$ symmetry that are severer than the LEP bound. We then explore relic density of a Majorana dark matter candidate without conflict of constraints from lepton flavor violating processes. A global analysis is carried out to search for parameters which can accommodate with observed data.