Stochastic Inflation at NNLO

Cohen, Timothy; Green, Daniel; Premkumar, Akhil; Ridgway, Alexander K.

doi:10.1007/jhep09(2021)159

Cited by 32 publications

(32 citation statements)

References 66 publications

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“…In the light physical mass regime and when the non-perturbativity is due to IR divergences both approaches should work. Then the eigenvalues of the Starobinski operator, computed to a subleading order in [3] (see also [105,106]), should manifest themselves as poles in the spectral density, discussed in the appendix C, for iν ∈ (0, d 2 ). In [77] we will show that it is indeed the case, providing an interesting check of both techniques.…”

Section: Summary and Future Directionsmentioning

confidence: 99%

Analyticity and unitarity for cosmological correlators

Pietro

Gorbenko

Komatsu

2022

J. High Energ. Phys.

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We study the fundamentals of quantum field theory on a rigid de Sitter space. We show that the perturbative expansion of late-time correlation functions to all orders can be equivalently generated by a non-unitary Lagrangian on a Euclidean AdS geometry. This finding simplifies dramatically perturbative computations, as well as allows us to establish basic properties of these correlators, which comprise a Euclidean CFT. We use this to infer the analytic structure of the spectral density that captures the conformal partial wave expansion of a late-time four-point function, to derive an OPE expansion, and to constrain the operator spectrum. Generically, dimensions and OPE coefficients do not obey the usual CFT notion of unitarity. Instead, unitarity of the de Sitter theory manifests itself as the positivity of the spectral density. This statement does not rely on the use of Euclidean AdS Lagrangians and holds non-perturbatively. We illustrate and check these properties by explicit calculations in a scalar theory by computing first tree-level, and then full one- loop-resummed exchange diagrams. An exchanged particle appears as a resonant feature in the spectral density which can be potentially useful in experimental searches.

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Section: Summary and Future Directionsmentioning

confidence: 99%

Analyticity and unitarity for cosmological correlators

Pietro

Gorbenko

Komatsu

2022

J. High Energ. Phys.

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“…An approach to deal with these IR effects has been known for a long time [224], but has not been developed systematically. For light scalars decoupled from gravity this was rectified in [225], and confirmed and extended using related but different techniques in [226][227][228][229][230][231]. The main conclusion is that strong IR effects are physical, can be controlled and calculated, and can lead to nonperturbative effects with observable consequences.…”

Section: Strong Ir Effectsmentioning

confidence: 69%

Snowmass White Paper: Cosmology at the Theory Frontier

Flauger¹,

Gorbenko²,

Joyce³

et al. 2022

Preprint

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The precision cosmological model describing the origin and expansion history of the universe, with observed structure seeded at the inflationary cosmic horizon, demands completion in the ultraviolet and in the infrared. The dynamics of the cosmic horizon also suggests an associated entropy, again requiring a microphysical theory. Recent years have seen enormous progress in understanding the structure of de Sitter space and inflation in string theory, and of cosmological observables captured by quantum field theory and solvable deformations thereof. The resulting models admit ongoing observational tests through measurements of the cosmic microwave background and large-scale structure, as well as through analyses of theoretical consistency by means of thought experiments. This paper, prepared for the TF01 and TF09 conveners of the Snowmass 2021 process, provides a synopsis of this important area, focusing on ongoing developments and opportunities.

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“…It would also be interesting to incorporate extensions of the stochastic-inflation equations beyond the leading order in sub-Hubble interactions (see, e.g., Refs. [79][80][81][82][83]) into our formalism.…”

Section: Discussionmentioning

confidence: 99%

Statistics of coarse-grained cosmological fields in stochastic inflation

Tada,

Vennin

2021

Preprint

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We present a generic framework to compute the one-point statistics of cosmological perturbations, when coarse-grained at an arbitrary scale R, in the presence of quantum diffusion. Making use of the stochastic-δN formalism, we show how it can be related to the statistics of the amount of expansion realised until the scale R crosses out the Hubble radius. This leads us to explicit formulae for the probability density function (PDF) of the curvature perturbation, the comoving density contrast, and the compaction function. We then apply our formalism to the calculation of the mass distribution of primordial black holes produced in a single-field model containing a "quantum well" (i.e. an exactly flat region in the potential). We confirm that the PDFs feature heavy, exponential tails, with an additional cubic suppression in the case of the curvature perturbation. The large-mass end of the mass distribution is shown to be mostly driven by stochastic-contamination effects, which produce black holes more massive than those naively expected. This work bridges the final gap between the stochastic-inflation formalism and the calculation of the mass distribution of astrophysical objects such as primordial black holes, and opens up various prospects that we finally discuss.

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Stochastic Inflation at NNLO

Cited by 32 publications

References 66 publications

Analyticity and unitarity for cosmological correlators

Analyticity and unitarity for cosmological correlators

Snowmass White Paper: Cosmology at the Theory Frontier

Statistics of coarse-grained cosmological fields in stochastic inflation

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