Cogenesis by a sliding pNGB with symmetry non-restoration

TL;DR

This paper proposes a novel mechanism where a pseudo-Nambu-Goldstone boson with a non-restored symmetry at high temperature can generate baryon asymmetry and dark matter through a sliding phase, with testable predictions for particle masses.

Contribution

It introduces a new baryogenesis and dark matter production scenario involving a sliding pNGB with non-restored symmetry, including detailed particle property predictions and experimental tests.

Findings

Predicted pNGB mass ~5 eV and decay constant ~3×10^6 GeV.

Radial mode mass around 10 MeV with small Higgs mixing.

Testable predictions for neutrino and collider experiments.

Abstract

We demonstrate that a pseudo-Nambu-Goldstone boson (pNGB) with an initial misalignment angle can drive successful spontaneous baryogenesis and serve as a dark matter (DM) candidate, provided the corresponding global symmetry is non-restored at high temperature. A key feature of this mechanism is the presence of a slowly sliding phase in the pNGB's motion, during which it traverses rapidly diminishing potential barriers, generating and freezing the baryon asymmetry, while transitioning into the kination phase and then an oscillatory phase. Just before the `would-be' oscillation temperature, parametric resonance effectively fragments the homogeneous mode into fluctuations that ultimately constitute the final DM abundance. By considering a dimension-five explicit breaking operator, we find that the predicted pNGB mass and decay constant are approximately $5\,{\rm eV}$ and $3\times10^6\,{\rm GeV}$, respectively, while the radial mode has a light mass $\mathcal{O}(10)\,{\rm MeV}$ and a small mixing $\mathcal{O}(10^{-4})$ with the Higgs boson. Applied to the Majoron in the type-I seesaw model, this scenario requires the heaviest right-handed neutrino to be as light as $0.1$ to $100\,{\rm GeV}$. These predictions can be tested through kaon experiments, heavy neutral lepton searches, the LHC, and future colliders.