Model-independent approach to effective sound speed in multi-field inflation
| Autor: | Antonio Enea Romano, Krzysztof Turzyński, Sergio Andrés Vallejo-Peña |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
High Energy Physics - Theory
Astrophysics and Astronomy Cosmology and Nongalactic Astrophysics (astro-ph.CO) Physics and Astronomy (miscellaneous) High Energy Physics - Theory (hep-th) General Relativity and Cosmology FOS: Physical sciences General Relativity and Quantum Cosmology (gr-qc) Engineering (miscellaneous) General Relativity and Quantum Cosmology Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | European Physical Journal |
| DOI: | 10.48550/arxiv.2006.00969 |
| Popis: | For any physical system satisfying the Einstein's equations, the comoving curvature perturbations satisfy an equation involving the momentum-dependent effective sound speed, valid for any system with a well defined energy-stress tensor, including multi-fields models of inflation. We derive a general model-independent formula for the effective sound speed of comoving adiabatic perturbations, valid for a generic field-space metric, without assuming any approximation to integrate out entropy perturbations, but expressing the momentum-dependent effective sound speed in terms of the components of the total energy-stress tensor. As an application, we study a number of two-field models with a kinetic coupling between the fields, identifying the single curvature mode of the effective theory and showing that momentum-dependent effective sound speed fully accounts for the predictions for the power spectrum of curvature perturbations. Our results show that the momentum-dependent effective sound speed is a convenient scheme for describing all inflationary models that admit a single-field effective theory, including the effects of entropy perturbations present in multi-fields systems. Comment: 19 pages, fig. 6 |
| Databáze: | OpenAIRE |
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