Nambu-Goldstone Dark Matter in a Scale Invariant Bright Hidden Sector

TL;DR

This paper explores a scale-invariant extension of the Standard Model with a hidden sector where Nambu-Goldstone bosons act as dark matter candidates, analyzing their properties and viable parameter spaces under different symmetry breaking scenarios.

Contribution

It introduces a novel dark matter model based on a strongly interacting hidden sector with dynamical symmetry breaking, detailing the effects of different symmetry breaking patterns on dark matter properties.

Findings

Distinct viable parameter spaces for different symmetry breaking patterns.

Significant differences in dark matter annihilation mechanisms between cases.

Identification of conditions under which Nambu-Goldstone bosons serve as dark matter.

Abstract

We consider a scale invariant extension of the standard model (SM) with a combined breaking of conformal and electroweak symmetry in a strongly interacting hidden $SU(n_c)$ gauge sector with $n_f$ vector-like hidden fermions. The (pseudo) Nambu-Goldstone bosons that arise due to dynamical chiral symmetry breaking are dark matter (DM) candidates. We focus on $n_f=n_c=3$, where $SU(3)$ is the largest symmetry group of hidden flavor which can be explicitly broken into either $U(1) \times U(1)$ or $SU(2)\times U(1)$. We study DM properties and discuss consistent parameter space for each case. Because of different mechanisms of DM annihilation the consistent parameter space in the case of $SU(2)\times U(1)$ is significantly different from that of $SU(3)$ if the hidden fermions have a SM $U(1)_Y$ charge of $O(1)$.