The hand-made tail: Non-perturbative tails from multifield inflation

Achucarro, Ana; Cespedes, Sebastian; Davis, Anne-Christine; Palma, Gonzalo A.

doi:10.48550/arxiv.2112.14712

Cited by 2 publications

(4 citation statements)

References 72 publications

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“…As demonstrated in our study, the fully nonlinear mapping between R and δφ plays a key role for the tail of the PDF. Meanwhile, the stochastic effects during inflation may also lead to nontrivial non-Gaussian tails [13][14][15][16][17]. Thus it is encouraging to extend our current analysis to incorporate more general considerations.…”

Section: Discussionmentioning

confidence: 87%

“…Except for the n-point correlators, there in principle exist significant phenomenological implications in the probability distribution of curvature perturbations that are not captured by perturbative approaches (see [7][8][9][10][11][12][13][14][15][16][17] for recent discussions). In particular, the perturbation theory breaks down at the tail of the distribution where fluctuations are large and rare.…”

Section: Introductionmentioning

confidence: 99%

“…R(τ c − ) = R(τ c + ), R(τ d − ) = R(τ d + ) and R (τ c − ) = R (τ c + ), R (τ d − ) = R (τ d + ).This gives the following behaviour of curvature perturbationsR k (τ ) = α r k H ikτ )e −ikτ + β r k H ikτ )e ikτ , τ c < τ < τ d , (B.25) R k (τ ) = α k H ikτ )e −ikτ + β k H ikτ )e ikτ , τ > τ d , ikτ )e ikτ , τ c < τ < τ d (B.27) R k (τ ) =α k H ikτ )e −ikτ + β k H ikτ )e ikτ , τ > τ d ,(B.28)where α r k , α k , β r k and β k are given by Eq. (B 16…”

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confidence: 99%

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Highly non-Gaussian tails and primordial black holes from single-field inflation

Cai¹,

Ma²,

Sasaki³

et al. 2022

Preprint

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For primordial perturbations, deviations from Gaussian statistics on the tail of the probability distribution can be associated with non-perturbative effects of inflation. In this paper, we present some particular examples in which the tail of the distribution becomes highly non-Gaussian although the statistics remains almost Gaussian in the perturbative regime. We begin with an extension of the ultra-slow-roll inflation that incorporates a transition process, where the inflaton climbs up a tiny potential step at the end of the non-attractor stage before it converges to the slow-roll attractor. Through this example, we identify the key role of the off-attractor behaviour for the upward-step transition, and then extend the analysis to another type of the transition with two slow-roll stages connected by a tiny step. We perform both the perturbative and non-perturbative analyses of primordial fluctuations generated around the step in detail, and show that the tiny but nontrivial transition may affect large perturbations in the tail of the distribution, while the perturbative non-Gaussianity remains small. Our result indicates that the non-Gaussian tails can have rich phenomenology which has been overlooked in conventional analyses. We also study the implications of this non-Gaussian tail for the formation of primordial black holes, and find that their mass fraction can be parametrically amplified by several orders of magnitudes in comparison with the case of the Gaussian distribution. Additionally, we also discuss a mechanism of primordial black holes formation for this upward step inflation model by trapping the inflaton in the bottom of the step.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Highly non-Gaussian tails and primordial black holes from single-field inflation

Cai¹,

Ma²,

Sasaki³

et al. 2022

Preprint

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“…See [25] for further discussions. We leave the studies of the diffusion-dominated regime for future work; for relevant works on this direction, see [32][33][34][35].…”

Section: The Model and The Background Evolutionmentioning

confidence: 99%

Multiple Field Ultra Slow Roll Inflation: Primordial Black Holes From Straight Bulk And Distorted Boundary

Hooshangi,

Talebian,

Namjoo

et al. 2022

Preprint

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We study a model of two-field ultra-slow-roll (USR) inflation bounded by a curve in the field space. Curvature perturbations and non-Gaussianities can be enhanced both during the USR phase and from the inhomogeneities at the boundary. We employ the full non-linear δN formalism to calculate the probability distribution function (PDF) for curvature perturbation non-perturbatively and show that the non-linear effects can significantly enhance the abundance of the primordial black holes (PBHs). For large curvature perturbations, the PDF has a universal exponential tail, but for the intermediate values, the PDF-and, therefore, the abundance of the PBHs-depend sensitively on the geometry of the boundary.

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The hand-made tail: Non-perturbative tails from multifield inflation

Cited by 2 publications

References 72 publications

Highly non-Gaussian tails and primordial black holes from single-field inflation

Highly non-Gaussian tails and primordial black holes from single-field inflation

Multiple Field Ultra Slow Roll Inflation: Primordial Black Holes From Straight Bulk And Distorted Boundary

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