2010/04/30 by David Kaiser, David I. Kaiser, Audrey T. Todhunter · 44 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Classical mechanics #Cosmology and Gravitation Theories #Economics #Inflation (cosmology) #Keynesian economics #Physics #Solar and Space Plasma Dynamics #Theoretical physics #astro-ph.CO #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.81.124037
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 81(12) (American Physical Society) · 16 pages, no figures. References added to match published version
openalex publication_date 2010/06/18 · arxiv created 2010/09/24 · arxiv updated 2010/09/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Realistic models of particle physics include many scalar fields. These fields generically have nonminimal couplings to the Ricci curvature scalar, either as part of a generalized Einstein theory or as necessary counterterms for renormalization in curved background spacetimes. We develop a gauge-invariant formalism for calculating primordial perturbations in models with multiple nonminimally coupled fields. We work in the Jordan frame (in which the nonminimal couplings remain explicit) and identify two distinct sources of entropy perturbations for such models. One set of entropy perturbations arises from interactions among the multiple fields. The second set arises from the presence of nonminimal couplings. Neither of these varieties of entropy perturbations will necessarily be suppressed in the long-wavelength limit, and hence they can amplify the curvature perturbation \ensuremathζ, even for modes that have crossed outside the Hubble radius. Models that overproduce long-wavelength entropy perturbations endanger the close fit between predicted inflationary spectra and empirical observations.