Primordial Black Holes from Sound Speed Resonance during Inflation

Cai, Yi-Fu; Tong, Xi; Wang, Dong-Gang; Yan, Sheng

doi:10.1103/physrevlett.121.081306

Cited by 171 publications

(191 citation statements)

References 57 publications

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“…We now study the formation of PBHs due to enhancement in the primordial power spectrum in the inflaton-curvaton mixed scenario (3.29), the analysis is quite similar with [47]. From Fig.…”

Section: Pbh Formationmentioning

confidence: 65%

“…Note that several minor peaks of the power spectrum of primordial density perturbations on smaller scales are also predicted by this mechanism. It was found in [47] that the formation of PBHs caused by the resulting peaks in SSR mechanism could be very efficient, which could be testable in the future observational experiments.…”

Section: Introductionmentioning

confidence: 94%

“…We focus on the characteristic mode k c (1 + ξ)k * , the parameter λ evolves as λ(τ ) λ(τ i )e −ξkcτ i function at the beginning of resonance to the BD vacuum, v k (τ i ) = e −ikτ i / √ 2k. The enhancement factor e −ξkcτ i arises from the interplay of two effects as discussed in [47]: the oscillation in the sound speed, controlled by its amplitude ξ; and the expansion of the Universe from the beginning of the resonance to the Hubble crossing of k c , i.e., v ≡ −k c τ i = τ i /τ c e ∆N , where ∆N is the e-folding number for this period of inflation. The numerical results show that the peaks for harmonic frequencies 2k c , 3k c , · · · are suppressed by a factor of around O(10 −8 ), so they can be safely neglected.…”

Section: Primordial Density Perturbation With a Peakmentioning

confidence: 99%

“…Recently, a novel mechanism for PBH formation by virtue of sound speed resonance (SSR) was proposed in [47]. According to this mechanism, it was found that an oscillating sound speed square could yield non-perturbative parametric amplification on certain perturbation modes during inflation.…”

Section: Introductionmentioning

confidence: 99%

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Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario

Chen

Cai

2019

J. Cosmol. Astropart. Phys.

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We study sound speed resonance (SSR) mechanism for primordial black hole (PBH) formation in an early universe scenario with inflaton and curvaton being mixed. In this scenario, the total primordial density perturbations could be contributed by the fluctuations from both the inflaton and curvaton fields, in which the inflaton fluctuations lead to the standard adiabatic perturbations, while the sound speed of the curvaton fluctuations are assumed to be oscillating during inflation. Due to the narrow resonance effect of SSR mechanism, we acquire the enhanced primordial density perturbations on small scales and they remain nearly scale-invariant on large scales, which is essential for PBH formation. Finally, we find that the PBHs with specific mass spectrum can be produced with a sufficient abundance for dark matter in the mixed scenario.

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“…We now study the formation of PBHs due to enhancement in the primordial power spectrum in the inflaton-curvaton mixed scenario (3.29), the analysis is quite similar with [47]. From Fig.…”

Section: Pbh Formationmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 94%

Section: Primordial Density Perturbation With a Peakmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario

Chen

Cai

2019

J. Cosmol. Astropart. Phys.

Self Cite

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“…The mechanisms of amplifying the small-scale curvature perturbations within the infla- 1 It is worthing pointing out that the scalar induced GWs are gauge independent [26][27][28]. tionary scenario have been extensively studied in recent years [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. The most common mechanism is the single-field inflection-point inflation [38][39][40][41][42][43][44][45], which requires that the potential of the inflaton field has an approximate inflection point.…”

Section: Introductionmentioning

confidence: 99%

Scalar induced gravitational waves in inflation with gravitationally enhanced friction

2020

Phys. Rev. D

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We study the scalar induced gravitational wave (GW) background in inflation with gravitationally enhanced friction (GEF). The GEF mechanism, which is realized by assuming a nonminimal derivative coupling between the inflaton field and gravity, is used to amplify the small-scale curvature perturbations to generate a sizable amount of primordial black holes. We find that the GW energy spectra can reach the detectable scopes of the future GW projects, and the power spectrum of curvature perturbations has a power-law form in the vicinity of the peak. The scaling of the GW spectrum in the ultraviolet regions is two times that of the power spectrum slope, and has a lower bound. In the infrared regions, the slope of the GW spectrum can be described roughly by a log-dependent form. These features of the GW spectrum may be used to check the GEF mechanism if the scalar induced GWs are detected in the future.

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Inflationary Krylov complexity

Li,

Liu

2024

J. High Energ. Phys.

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In this work, we have systematically investigated the Krylov complexity of curvature perturbation for the modified dispersion relation in inflation, using the algorithm in closed system and open system. Since many quantum gravitational frameworks could lead to this kind of modified dispersion relation, our analysis could be applied to the string cosmology, loop gravity, e.t.c. Following the Lanczos algorithm, we find the very early universe is an infinite, many-body, and maximal chaotic system. Our numerics shows that the Lanczos coefficient and Lyapunov index of the standard dispersion relation are mainly determined by the scale factor. As for the modified case, it is nearly determined by the momentum. In a method of the closed system, we discover that the Krylov complexity will show irregular oscillation before the horizon exits. The modified case will present faster growth after the horizon exists. Since the whole universe is an open system, the approach of an open system is more realistic and reliable. Then, we construct the exact wave function which is very robust only requiring the Lanczos coefficient proportional to n (main quantum number). Based on it, we find the Krylov complexity and Krylov entropy could nicely recover in the case of a closed system under the weak dissipative approximation, in which our analysis shows that the evolution of Krylov complexity will not be the same with the original situation. We also find the inflationary period is a strong dissipative system. Meanwhile, our numerics clearly shows the Krylov complexity will grow during the whole inflationary period. But for the small scales, there will be a peak after the horizon exits. Our analysis reveals that the dramatic change in background (inflation) will significantly impact the evolution of Krylov complexity. Since the curvature perturbation will transit from the quantum level to the classical level. We could expect that the decoherence will highly impact the Krylov complexity during inflation.

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Primordial Black Holes from Sound Speed Resonance during Inflation

Cited by 171 publications

References 57 publications

Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario

Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario

Scalar induced gravitational waves in inflation with gravitationally enhanced friction

Inflationary Krylov complexity

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