Heavy fields, reduced speeds of sound, and decoupling during inflation
| Autor: | Subodh P. Patil, Vicente Atal, Ana Achúcarro, Sebastian Cespedes, Gonzalo A. Palma, Jinn Ouk Gong |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
High Energy Physics - Theory
Physics Nuclear and High Energy Physics Quantum field theory in curved spacetime Cosmology and Nongalactic Astrophysics (astro-ph.CO) 010308 nuclear & particles physics FOS: Physical sciences Decoupling (cosmology) General Relativity and Quantum Cosmology (gr-qc) Curvature 01 natural sciences General Relativity and Quantum Cosmology High Energy Physics - Phenomenology Classical mechanics High Energy Physics - Phenomenology (hep-ph) High Energy Physics - Theory (hep-th) Speed of sound Non-Gaussianity 0103 physical sciences Effective field theory 010306 general physics Adiabatic process Mass gap Particle Physics - Theory Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Physical Review D, 86(12), 121301 |
| Popis: | We discuss and clarify the validity of effective single field theories of inflation obtained by integrating out heavy degrees of freedom in the regime where adiabatic perturbations propagate with a suppressed speed of sound. We show by construction that it is indeed possible to have inflationary backgrounds where the speed of sound remains suppressed and slow-roll persists for long enough. In this class of models, heavy fields influence the evolution of adiabatic modes in a manner that is consistent with decoupling of physical low and high energy degrees of freedom. We emphasize the distinction between the effective masses of the isocurvature modes and the eigenfrequencies of the propagating high energy modes. Crucially, we find that the mass gap that defines the high frequency modes increases with the strength of the turn, even as the naive heavy (isocurvature) and light (curvature) modes become more strongly coupled. Adiabaticity is preserved throughout, and the derived effective field theory remains in the weakly coupled regime, satisfying all current observational constraints on the resulting primordial power spectrum. In addition, these models allow for an observably large equilateral non-Gaussianity. Comment: 8 pages, v2: minor changes, typos corrected |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|