Gamma-ray Line from Nambu-Goldstone Dark Matter in a Scale Invariant Extension of the Standard Model

TL;DR

This paper proposes a scale-invariant extension of the Standard Model with a dark matter candidate that can produce gamma-ray lines through annihilation, linking astrophysical signals with collider tests.

Contribution

It introduces a novel dark matter candidate from a hidden sector with hypercharge, capable of producing gamma-ray lines and being testable at colliders.

Findings

Gamma-ray line energy between 0.7 and 0.9 TeV.

Annihilation cross section range of 10^{-30} to 10^{-26} cm^3/s.

Potential collider signatures due to non-zero hypercharge Q.

Abstract

A recently proposed scale invariant extension of the standard model is modified such that it includes a Dark Matter candidate which can annihilate into gamma-rays. For that a non-zero $U(1)_Y$ hypercharge $Q$ is assigned to the fermions in a QCD-like hidden sector. The Nambu-Goldstone bosons, that arise due to dynamical chiral symmetry breaking in the hidden sector, are cold Dark Matter candidates, and the extension allows them to annihilate into two photons, producing a gamma-ray line spectrum. We find that the gamma-ray line energy must be between 0.7 TeV and 0.9 TeV with the velocity-averaged annihilation cross section $10^{-30}\sim 10^{-26}$ cm^3/s for $Q=1/3$. With a non-zero hypercharge $Q$, the hidden sector is no longer completely dark and can be directly probed by collider experiments.