Gravitational Waves and Primordial Black Holes from Supersymmetric Hybrid Inflation

Cosmological perturbations, originating in the quantum fluctuations of the fields that drive inflation, are observed to be nearly scale invariant at the largest scales. At smaller scales, however, perturbations are not severely constrained and might be of particular importance if their amplitude is large. They can trigger the creation of primordial black holes (PBHs) or stochastic gravitational waves (GWs). Small-scale perturbations are generated during the later stages of inflation, when possible strong features in the inflaton potential can break scale invariance and leave characteristic imprints on the spectrum. We focus on and review three types of features: inflection points and steep steps in the potential, as well as sharp turns in the inflationary trajectory in field space. We show that such features induce a strong enhancement of the curvature spectrum within a certain wavenumber range. In particular cases, they also generate characteristic oscillatory patterns that are transferred in the spectrum of secondary GWs, which are potentially observable by operating or designed experiments. We demonstrate these effects through the calculation of the primordial power spectrum and the PBH abundance in the context of α-attractors and supergravity (SUGRA) models of inflation.

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“…Other mechanisms and model building directions also exist, and particular set ups can be found in refs. [46][47][48], just to mention a few.…”

Section: Amplificationmentioning

confidence: 99%

Features of the inflaton potential and the power spectrum of cosmological perturbations

et al. 2021

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“…Between them, the metastable cosmic strings are currently of special interest since they may decay generating a stochastic background of gravitational waves [17,18] and interpreting, thereby, recent results [19,20] -for other sources of gravitational waves' production after the end of HI see Refs. [21,22].…”

Section: Introductionmentioning

confidence: 99%

E- and T-model hybrid inflation

Pallis

2023

Eur. Phys. J. C

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We consider the impact of a kinetic pole of order one or two on the non-supersymmetric model of hybrid inflation. These poles arise due to logarithmic Kähler potentials which control the kinetic mixing of the inflaton field and parameterize hyperbolic manifolds with scalar curvature related to the coefficient $$(-N)<0$$ ( - N ) < 0 of the logarithm. Inflation is associated with the breaking of a local $$SU(2)\times U(1)$$ S U ( 2 ) × U ( 1 ) symmetry, which does not produce any cosmological defects after it, and remains largely immune from the minimal possible radiative corrections to the inflationary potential. For $$N=1$$ N = 1 and equal values of the relevant coupling constants, $$\lambda $$ λ and $$\kappa $$ κ , the achievement of the observationally central value for the scalar spectral index, $$n_{\textrm{s}}$$ n s , requires the mass parameter, m, and the symmetry breaking scale, M, to be of the order of $$10^{12}~{\textrm{GeV}}$$ 10 12 GeV and $$10^{17}~{\textrm{GeV}}$$ 10 17 GeV respectively. Increasing N above unity the tensor-to-scalar ratio r increases above 0.002 and reaches its maximal allowed value for $$N\simeq 10{-}20$$ N ≃ 10 - 20 .

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“…Besides, the single field model with a non-canonical kinetic term containing a peak coupling function is also an efficient way to amplify the power spectrum [37][38][39][40][41][42][43]. And recently, inflation driven by two-field to produce PBHs and SIGWs is very appealing [44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Primordial black holes and scalar induced gravitational waves from the $E$ model with a Gauss-Bonnet term

Zhang

2021

Preprint

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Inspired by the possibility that the important role from higher-order curvature correction of gravity is non-negligible during the early universe, we consider E-model inflation with a coupling between inflaton and the Gauss-Bonnet term. With the help of the Gauss-Bonnet term, the Emodel potential with different indexes can drive inflation and enhance the amplitude of the power spectrum of curvature perturbations to O(10 −2 ) at peak scales, which is large enough to produce a significant abundance of primordial black holes and observational scalar induced gravitational waves. With different parameters, the produced primordial black holes can explain the LIGO-Virgo events, the ultrashort-timescale microlensing events in the OGLE data, or consist of almost all the dark matter. The produced scalar induced gravitational waves can be detected by space-based gravitational wave observatories, like LISA, TianQin, and Pulsar Timing Array. Especially, our model also produces scalar induced gravitational waves that can explain the recent NANOGrav signal. We also compute the non-Gaussianity of this model and discuss its impacts on primordial black holes and scalar induced gravitational waves furthermore. The formation of PBHs is easier taking into account of non-Gaussianity, on the contrary, the energy density of scalar induced gravitational waves is almost unaffected by non-Gaussianity.

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Gravitational Waves and Primordial Black Holes from Supersymmetric Hybrid Inflation

Cited by 3 publications

References 100 publications

Features of the inflaton potential and the power spectrum of cosmological perturbations

Features of the inflaton potential and the power spectrum of cosmological perturbations

E- and T-model hybrid inflation

Primordial black holes and scalar induced gravitational waves from the $E$ model with a Gauss-Bonnet term

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