REVIEW 8 cited by
On the IR Divergences in de Sitter Space: loops, resummation and the semi-classical wavefunction
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
read the original abstract
In this paper, we revisit the infrared (IR) divergences in de Sitter (dS) space using the wavefunction method, and explicitly explore how the resummation of higher-order loops leads to the stochastic formalism. In light of recent developments of the cosmological bootstrap, we track the behaviour of these nontrivial IR effects from perturbation theory to the non-perturbative regime. Specifically, we first examine the perturbative computation of wavefunction coefficients, and show that there is a clear distinction between classical components from tree-level diagrams and quantum ones from loop processes. Cosmological correlators at loop level receive contributions from tree-level wavefunction coefficients, which we dub classical loops. This distinction significantly simplifies the analysis of loop-level IR divergences, as we find the leading contributions always come from these classical loops. Then we compare with correlators from the perturbative stochastic computation, and find the results there are essentially the ones from classical loops, while quantum loops are only present as subleading corrections. This demonstrates that the leading IR effects are contained in the semi-classical wavefunction which is a resummation of all the tree-level diagrams. With this insight, we go beyond perturbation theory and present a new derivation of the stochastic formalism using the saddle-point approximation. We show that the Fokker-Planck equation follows as a consequence of two effects: the drift from the Schr\"odinger equation that describes the bulk time evolution, and the diffusion from the Polchinski's equation which corresponds to the exact renormalization group flow of the coarse-grained theory on the boundary. Our analysis highlights the precise and simple link between the stochastic formalism and the semi-classical wavefunction.
Forward citations
Cited by 8 Pith papers
-
On Cosmological Correlators at One Loop
The one-loop triangle in-in correlator of massless scalars in flat space is evaluated in closed form in terms of dilogarithms, with Landau analysis revealing its physical singularities and a partial-energy factorisati...
-
Stochastic inflation from a non-equilibrium renormalization group
Stochastic inflation is the leading infrared limit of a coarse-grained Schwinger–Keldysh effective theory, and the same Fokker–Planck dynamics follows from a Polchinski-type renormalization-group flow for the reduced ...
-
Confronting infrared divergences in de Sitter: loops, logarithms and the stochastic formalism
The authors show that loop corrections do not alter tree-level time dependence in de Sitter correlators, so secular growth is a regularization artifact, not a physical effect.
-
Renormalisation and matching of massless scalar correlation functions in Soft de Sitter Effective Theory
SdSET is shown to renormalise and match like a flat-space EFT: tree-level trispectrum and six-point matching plus a one-loop power-spectrum match determine the SdSET couplings and initial-condition functions.
-
Stochastic inflation as an open quantum system
Stochastic inflation emerges from an open-quantum-system derivation, with a Lindblad master equation that reduces to and corrects Starobinsky's Fokker-Planck equation.
-
Stochastic inflation as a superfluid
Inflationary superhorizon fluctuations obey superfluid-type continuity and Euler equations, with quantum pressure becoming relevant in ultra-slow-roll phases.
-
Efficient training of photonic quantum generative models
Photonic quantum generative models can be trained classically via maximum mean discrepancy, with deployment corresponding to boson sampling.
-
Lectures on Open Systems and Cosmology
A pedagogical review that presents the density-matrix/master-equation formalism and the Schwinger–Keldysh path integral in one notation and applies them to inflation; it claims no new result.
Discussion (0). Sign in to comment.