Scale-invariance as the origin of dark radiation?

Abstract

Recent cosmological data favour R^2-inflation and some amount of non-standard dark radiation in the Universe. We show that a framework of high energy scale invariance can explain these data. The spontaneous breaking of this symmetry provides gravity with the Planck mass and particle physics with the electroweak scale. We found that the corresponding massless Nambu--Goldstone bosons -- dilatons -- are produced at reheating by the inflaton decay right at the amount needed to explain primordial abundances of light chemical elements and anisotropy of the cosmic microwave background. Then we extended the discussion on the interplay with Higgs-inflation and on general class of inflationary models where dilatons are allowed and may form the dark radiation. As a result we put a lower limit on the reheating temperature in a general scale invariant model of inflation.

15 pages, 4 figures; v2: replaced with revised version recently published

References in corpus (8)

• The Standard Model Higgs boson as the inflaton
• Quantum scale invariance, cosmological constant and hierarchy problem
• Goldstone Bosons as Fractional Cosmic Neutrinos
• Primordial Bispectrum from Multifield Inflation with Nonminimal Couplings
• Scalaron the mighty: producing dark matter and baryon asymmetry at reheating
• A theory of extra radiation in the Universe
• Higgs-Dilaton cosmology: Are there extra relativistic species?
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• Dynamical analysis on $f(R,\mathcal{G})$ cosmology
• Observational constraints on Gauss-Bonnet cosmology
• Inflation and reheating in scale-invariant scalar-tensor gravity
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• Frame (In)equivalence in Quantum Field Theory and Cosmology
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• Radiative breaking of conformal symmetry in the Standard Model
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• Classical and quantum cosmology of $K$-essentially modified $R^2$ and pure $R^p$ gravity
• Relating the cosmological constant and slow roll to conformal symmetry breaking
• The Ambiguity in the Definition and Behavior of the Gravitational and Cosmological `Coupling Constants' in the Theory of Induced Gravity
• $p$-Branes with $Ad{S}_{p+1}$ vacuum as models of $R^2$ gravity
• Dark photons in the decay of Higgs-like boson
• Testing the Starobinsky model of inflation with resonant cavities