Multifield inflation beyond $N_\mathrm{field}=2$: non-Gaussianities and single-field effective theory
| Autor: | Lucas Pinol |
|---|---|
| Přispěvatelé: | Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
High Energy Physics - Theory
cosmological model Cosmology and Nongalactic Astrophysics (astro-ph.CO) Field (physics) fluctuation: adiabatic Scalar (mathematics) kinetic FOS: Physical sciences General Relativity and Quantum Cosmology (gr-qc) curvature: scalar field equations: linear entropy: fluctuation 01 natural sciences rotation General Relativity and Quantum Cosmology Theoretical physics 0103 physical sciences effect: geometrical Effective field theory Cosmological perturbation theory physics of the early universe multifield inflation structure 010306 general physics Inflation (cosmology) Physics inflation: effective field theory higher-order: 3 010308 nuclear & particles physics background [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th] matrix model Order (ring theory) Astronomy and Astrophysics Mass matrix primordial nongaussianities bispectrum field theory: scalar High Energy Physics - Theory (hep-th) non-Gaussianity [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc] curvature: perturbation [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] Astrophysics - Cosmology and Nongalactic Astrophysics Scalar curvature |
| Zdroj: | JCAP JCAP, 2021, 04, pp.002. ⟨10.1088/1475-7516/2021/04/002⟩ """JCAP, 2021, 04, pp.002. ⟨10.1088/1475-7516/2021/04/002⟩""" |
| DOI: | 10.1088/1475-7516/2021/04/002⟩ |
| Popis: | In this article, we study in detail the linear dynamics and cubic interactions for any number $N_\mathrm{field}$ of scalar fields during inflation, directly in terms of the observable curvature perturbation $\zeta$ and $N_\mathrm{field}-1$ entropic fluctuations, a choice that is more suitable for analytical works. In the linear equations of motion for the perturbations, we uncover rich geometrical effects beyond terms involving just the scalar curvature of the field space, and that come from the non-canonical kinetic structure of the scalar fields when the dimension of the field space is larger than two. Moreover, we show that a fast rotation of the local entropic basis can result in negative eigenvalues for the entropic mass matrix, potentially destabilising the background dynamics when $N_\mathrm{field} \geqslant 3$. We also explain how to render manifest the sizes of cubic interactions between the adiabatic and the entropic fluctuations, extending a previous work of ours to any number of interacting fields. As a first analytical application of our generic formalism, we derive the effective single-field theory for perturbations up to cubic order when all entropic fluctuations are heavy enough to be integrated out. In a slow-varying limit, we recover the cubic action expected from the effective field theory of inflation, but with a prediction for the usual Wilson coefficients in terms of the multifield parameters, thus proposing a new interpretation of the bispectrum in this generic $N_\mathrm{field}$ context. Comment: 30 pages, 1 figure |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|