On primordial black holes from an inflection point

By C. Germani, T. Prokopec. 2017

380 citations recorded by the source corpus.

Recently, it has been claimed that inflationary models with an inflection point in the scalar potential can produce a large resonance in the power spectrum of curvature perturbation. In this paper however we show that the previous analyses are incorrect. The reason is twofold: firstly, the inflaton is over-shot from a stage of standard inflation and so deviates from the slow-roll attractor before reaching the inflection. Secondly, on the (or close to) the inflection point, the ultra-slow-roll trajectory supersede the slow-roll one and thus, the slow-roll approximations used in the literature cannot be used. We then reconsider the model and provide a recipe for how to produce nevertheless a large peak in the matter power spectrum via fine-tuning of parameters.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a44c3fed49b4227343b5cf9b14a6fd8601953b4d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. R. Cai
2. J. Rubio
3. M. Hertzberg
4. Y. Gong
5. Zongkuan Guo
6. F. Pedro
7. V. A. Diaz
8. H. Di

In Nuclear and High Energy Physics

1. R. Cai
2. M. Hertzberg
3. J. Rubio
4. F. Pedro
5. V. A. Diaz
6. Y. Gong
7. Zongkuan Guo
8. H. Di

Citations in the corpus

• Generating PBHs and small-scale GWs in two-field models of inflation (2020, background): “This can be achieved in single-field inflation scenarios by using a local feature in the inflaton potential like a rapid change of its amplitude or a break in its first derivative [7–9], an inflection point [10–18] or a tiny bump superimposed on it [19, 20], non-trivial inflaton sound speed [21–23]1”
• Primordial black holes and second order gravitational waves from ultra-slow-roll inflation (2017, background): “For typical potentials with a inflection point, the problem is that inflation either ends or the slow-roll condition is violated before reaching the near inflection point [23, 25, 37].”
• Steepest growth of the power spectrum and primordial black holes (2018, methodology): “As expected, the analytic approximation following from an instant matching between phases of inflation grows more steeply than the more realistic (and smooth) potential of [31].”
• Higgs Inflation (2018, background): “It is important to notice at this point that the standard slow-roll condition may break down if the potential becomes extremely flat and the inertial contribution in the equation of motion for the inflation field is not negligible as compared with the Hubble friction [155–157].”
• Primordial black holes from string inflation (2018, background): “As pointed out in [2, 16, 45, 46], the slow-roll approximation ceases to be valid in the near inflection point region.”
• Primordial black holes and gravitational waves from parametric amplification of curvature perturbations (2019, background): “This can be achieved through several ways, such as running mass inflationary models [59–61], multiple-field inflationary models [14, 62], ultra-slow-roll inflationary models [63–65] or sound speed resonance [66–68].”
• Primordial Black Holes from Polynomial Potentials in Single Field Inflation (2017, positive): “In particular, we find that the slow-roll condition has to be violated [35–40] and we can achieve this by having the inflaton overshoot a local minimum during inflation [38, 40].”