On the importance of heavy fields during inflation
| Autor: | Gonzalo A. Palma, Vicente Atal, Sebastian Cespedes |
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| Rok vydání: | 2012 |
| Předmět: |
Physics
Inflation (cosmology) High Energy Physics - Theory Cosmology and Nongalactic Astrophysics (astro-ph.CO) Spectral density FOS: Physical sciences Astronomy and Astrophysics Angular velocity General Relativity and Quantum Cosmology (gr-qc) Curvature Space (mathematics) Cosmology General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Phenomenology (hep-ph) High Energy Physics - Theory (hep-th) Effective field theory Cosmological perturbation theory Statistical physics Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Artículos CONICYT CONICYT Chile instacron:CONICYT |
| DOI: | 10.48550/arxiv.1201.4848 |
| Popis: | We study the dynamics of two-field models of inflation characterized by a hierarchy of masses between curvature and isocurvature modes. When the hierarchy is large, a low energy effective field theory (EFT) exists in which only curvature modes participate in the dynamics of perturbations. In this EFT heavy fields continue to have a significant role in the low energy dynamics, as their interaction with curvature modes reduces their speed of sound whenever the multi-field trajectory is subject to a sharp turn in target space. Here we analyze under which general conditions this EFT remains a reliable description for the linear evolution of curvature modes. We find that the main condition consists on demanding that the rate of change of the turn's angular velocity stays suppressed with respect to the masses of heavy modes. This adiabaticity condition allows the EFT to accurately describe a large variety of situations in which the multi-field trajectory is subject to sharp turns. To test this, we analyze several models with turns and show that, indeed, the power spectra obtained for both the original two-field theory and its single-field EFT are identical when the adiabaticity condition is satisfied. In particular, when turns are sharp and sudden, they are found to generate large features in the power spectrum, accurately reproduced by the EFT. Comment: 34 pages, 10 figures. v2: improved discussion on the validity of the EFT, added references. v3: minor changes, version as in JCAP |
| Databáze: | OpenAIRE |
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