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Why do cosmological perturbations look classical to us?

3 Pith papers cite this work. Polarity classification is still indexing.

3 Pith papers citing it
abstract

According to the inflationary scenario of cosmology, all structure in the Universe can be traced back to primordial fluctuations during an accelerated (inflationary) phase of the very early Universe. A conceptual problem arises due to the fact that the primordial fluctuations are quantum, while the standard scenario of structure formation deals with classical fluctuations. In this essay we present a concise summary of the physics describing the quantum-to-classical transition. We first discuss the observational indistinguishability between classical and quantum correlation functions in the closed system approach (pragmatic view). We then present the open system approach with environment-induced decoherence. We finally discuss the question of the fluctuations' entropy for which, in principle, the concrete mechanism leading to decoherence possesses observational relevance.

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hep-th 2 gr-qc 1

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UNVERDICTED 3

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representative citing papers

Schwinger-Keldysh Path Integral for Gauge theories

hep-th · 2026-04-29 · unverdicted · novelty 7.0 · 2 refs

Constructs a manifestly diagonal-BRST-invariant Schwinger-Keldysh path integral for open non-Abelian gauge theories with arbitrary physical initial states, yielding Ward-Takahashi-Slavnov-Taylor identities and a Keldysh BRST symmetry for the Open EFT.

Gauging Open EFTs from the top down

hep-th · 2025-12-18 · unverdicted · novelty 6.0

Derives gauge-invariant influence functionals for photons and Stueckelberg fields in open U(1) gauge EFTs via BRST on the in-in contour after integrating out matter.

On the Quantum-to-Classical Transition of Primordial Perturbations

gr-qc · 2019-06-29 · unverdicted · novelty 3.0

A dissertation that introduces slow-roll inflation and perturbations, critiques squeezing and decoherence formalisms, and investigates the pilot-wave approach to the quantum-to-classical transition with numerical illustrations.

citing papers explorer

Showing 3 of 3 citing papers.

  • Schwinger-Keldysh Path Integral for Gauge theories hep-th · 2026-04-29 · unverdicted · none · ref 121 · 2 links · internal anchor

    Constructs a manifestly diagonal-BRST-invariant Schwinger-Keldysh path integral for open non-Abelian gauge theories with arbitrary physical initial states, yielding Ward-Takahashi-Slavnov-Taylor identities and a Keldysh BRST symmetry for the Open EFT.

  • Gauging Open EFTs from the top down hep-th · 2025-12-18 · unverdicted · none · ref 51 · internal anchor

    Derives gauge-invariant influence functionals for photons and Stueckelberg fields in open U(1) gauge EFTs via BRST on the in-in contour after integrating out matter.

  • On the Quantum-to-Classical Transition of Primordial Perturbations gr-qc · 2019-06-29 · unverdicted · none · ref 12 · internal anchor

    A dissertation that introduces slow-roll inflation and perturbations, critiques squeezing and decoherence formalisms, and investigates the pilot-wave approach to the quantum-to-classical transition with numerical illustrations.