Axionic Co-genesis of Baryon, Dark Matter and Dark Radiation

Abstract

We argue that coherent oscillations of the axion field excited by the misalignment mechanism and non-thermal leptogenesis by the saxion decay can naturally explain the observed abundance of dark matter and baryon asymmetry, thus providing a solution to the baryon-dark matter coincidence problem. The successful axionic co-genesis requires a supersymmetry breaking scale of O(10^{6-7}) GeV, which is consistent with the recently discovered standard-model like Higgs boson of mass about 126 GeV. Although the saxion generically decays into a pair of axions, their abundance sensitively depends on the saxion stabilization mechanism as well as couplings with the Higgs field. We discuss various ways to make the saxion dominantly decay into the right-handed neutrinos rather than into axions, and show that the abundance of axion dark radiation can be naturally as small as ΔN_{\rm eff} \lesssim {\cal O}(0.1), which is allowed by the Planck data.

23 pages, 2 figures; v3: discussion extended, references added, published in JHEP

References in corpus (4)

• A theory of extra radiation in the Universe
• General treatment of isocurvature perturbations and non-Gaussianities
• Axions and saxions from the primordial supersymmetric plasma and extra radiation signatures
• Primordial Trispectrum from Isocurvature Fluctuations

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• Dark radiation and dark matter in supersymmetric axion models with high reheating temperature
• Baryogenesis with Higher Dimension Operators
• Axions as Hot and Cold Dark Matter
• A Parallel World in the Dark
• Is the CMB telling us that dark matter is weaker than weakly interacting?
• Moduli-induced Baryogenesis