Scale Invariant Extension of the Standard Model: A Nightmare Scenario in Cosmology

2024/01/23 by Mayumi Aoki, Aoki, Mayumi, Jisuke Kubo +3 · 1 citation
Physics and Astronomy · Computer Science · #Cosmology and Gravitation Theories #Particle physics theoretical and experimental studies #Computational Physics and Python Applications

paper · pdf · doi:10.48550/arxiv.2401.12442

Abstract

Inflationary observables of a classically scale invariant model, in which the origin of the Planck mass and the electroweak scale including the right-handed neutrino mass is chiral symmetry breaking in a QCD-like hidden sector, are studied. Despite a three-field inflation the initial-value-dependence is strongly suppressed thanks to a river-valley like potential. The model predicts the tensor-to-scalar ratio r of cosmological perturbations smaller than that of the R² inflation, i.e., 0.0044 \gsim r \gsim 0.0017 for e-foldings between 50 and 60: The model will be consistent even with a null detection at LiteBird/CMB-S4. We find that the non-Gaussianity parameter f_NL is O(10^-2), the same size as that of single-field inflation. The dark matter particles are the lightest Nambu-Goldstone bosons associated with chiral symmetry breaking, which are decay products of one of the inflatons and are heavier than 10⁹ GeV with a strongly suppressed coupling with the standard model, implying that the dark matter will be unobservable in direct as well as indirect measurements.

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• Gravitational waves from high-temperature vacuum decay in scale-invariant models: nanohertz vs. millihertz regimes

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