Conformal B-L and Pseudo-Goldstone Dark Matter

TL;DR

This paper presents a conformal B-L extended standard model where a pseudo-Goldstone boson acts as a long-lived dark matter candidate, linking neutrino mass, matter origin, and dark matter through hierarchical symmetry breaking.

Contribution

It introduces a novel conformal B-L model with two scalar VEVs, where the lower VEV's imaginary part serves as a pseudo-Goldstone dark matter, connecting multiple cosmological phenomena.

Findings

Dark matter relic density from freeze-in mechanism.

Dark matter mass predicted to be above 100 TeV.

Decays produce high-energy neutrinos detectable by IceCube.

Abstract

We show that a conformal extension of the standard model with local B-L symmetry and two complex scalars breaking B-L can provide a unified description of neutrino mass, origin of matter and dark matter. There are two hierarchical B-L breaking vacuum expectation value (VEV) scales in the model, the higher denoted by $v_B$ and the lower by $v_A$. The higher breaking scale is dynamically implemented via the Coleman-Weinberg mechanism and plays a key role in the model since it induces electroweak symmetry breaking as well as the lower B-L breaking scale. It is also responsible for neutrino masses via the seesaw mechanism and origin of matter. The imaginary part of the complex scalar with lower B-L breaking VEV plays the role of a pseudo-Goldstone dark matter (DM). The DM particle is unstable with its lifetime naturally longer than $10^{28}$ seconds. We show that its relic density arises from the freeze-in mechanism for a wide parameter domain. Due to the pseudo-Goldstone boson nature of the DM particle, the direct detection cross section is highly suppressed. The model also predicts the dark matter to be heavier than 100 TeV and it decays to two high energy neutrinos which can be observable at the IceCube, providing a test of this model.