Unavoidable shear from quantum fluctuations in contracting cosmologies

Autor: Vincent Vennin, Julien Grain

Publikováno v: European Physical Journal C: Particles and Fields, Vol 81, Iss 2, Pp 1-14 (2021)
European Physical Journal C: Particles and Fields
European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2021, 81 (2), pp.132. ⟨10.1140/epjc/s10052-021-08932-0⟩
Eur.Phys.J.C
Eur.Phys.J.C, 2021, 81 (2), pp.132. ⟨10.1140/epjc/s10052-021-08932-0⟩
European Physical Journal

Contracting cosmologies are known to be flawed with a shear instability, where the contribution from the anisotropic stress to the overall energy density grows as $a^{-6}$, with $a$ the scale factor. Classically, whether or not this contribution beco

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7da4e185fcb34b5d17606d8649e93d94
https://doaj.org/article/d5af982bb52d4464b1a4d9a07bfd4f63

Hamiltonian formalism for cosmological perturbations: the separate-universe approach

Autor: Artigas Guimarey, Danilo, Grain, Julien, Vennin, Vincent

Publikováno v: JCAP
JCAP, 2022, 02 (02), pp.001. ⟨10.1088/1475-7516/2022/02/001⟩

The separate-universe approach provides an effective description of cosmological perturbations at large scales, where the universe can be described by an ensemble of independent, locally homogeneous and isotropic patches. By reducing the phase space

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3188a029e95780f914a9ed3836c6ae69

High-frequency Graviton from Inflaton Oscillation

Autor: Ema, Yohei, Jinno, Ryusuke, Nakayama, Kazunori

We point out that there is a high-frequency tail of the stochastic inflationary gravitational wave background that scales as $f^{-1/2}$ with frequency $f$. This contribution comes from the graviton vacuum fluctuation amplified by the inflaton coheren

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::9b91e3bf5cad88f1b4980befb150ff09

Power spectrum in stochastic inflation

Autor: Vincent Vennin, Kenta Ando

Publikováno v: Journal of Cosmology and Astroparticle Physics
Journal of Cosmology and Astroparticle Physics, Institute of Physics (IOP), 2021, 04, pp.057. ⟨10.1088/1475-7516/2021/04/057⟩
JCAP
JCAP, 2021, 04, pp.057. ⟨10.1088/1475-7516/2021/04/057⟩

We compute the power spectrum of curvature perturbations in stochastic inflation. This combines the distribution of first crossing times through the end-of-inflation surface, which has been previously studied, with the distribution of the fields valu

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ef7322f5d03ce93241f407ed70fa92fd
https://doi.org/10.1088/1475-7516/2021/04/057

Stochastic inflation beyond slow roll

Autor: Hooshyar Assadullahi, Vincent Vennin, David Wands, Chris Pattison

Publikováno v: JCAP
JCAP, 2019, 07, pp.031. ⟨10.1088/1475-7516/2019/07/031⟩
Pattison, C, Vennin, V, Assadullahi, H & Wands, D 2019, ' Stochastic inflation beyond slow roll ', Journal of Cosmology and Astroparticle Physics, vol. 2019, no. 7, 031 . https://doi.org/10.1088/1475-7516/2019/07/031

We study the stochastic formalism of inflation beyond the usual slow-roll approximation. We verify that the assumptions on which the stochastic formalism relies still hold even far from the slow-roll attractor. This includes demonstrating the validit

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3bbaa52957706b9d45c7d245143b82bb
https://doi.org/10.1088/1475-7516/2019/07/031