2002/12/31 by Gerasimos Rigopoulos
Physics and Astronomy · #Adiabatic process #Black Holes and Theoretical Physics #Cosmological perturbation theory #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Geodesic #Gravitation #Gravitational field #Invariant (physics) #Metric (unit) #Nonlinear system #Perturbation (astronomy) #astro-ph #gr-qc
paper · pdf · doi:10.1088/0264-9381/21/7/002
published as Class.Quant.Grav.21:1737-1754,2004 · 19 pages, 1 figure; Substantial revision from earlier versions. Published in Classical and Quantum Gravity
openalex publication_date 2004/03/08 · arxiv created 2004/03/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present a method for the study of second-order superhorizon perturbations in multifield inflationary models with nontrivial kinetic terms. We utilize a change of coordinates in field space to separate isocurvature and adiabatic perturbations generalizing previous results. We also construct second-order gauge-invariant variables related to them. It is found that with an arbitrary metric in field space the isocurvature perturbation sources the gravitational potential on long wavelengths even for 'straight' trajectories. The potential decouples from the isocurvature perturbations if the background fields' trajectory is a geodesic in field space. Taking nonlinear effects into account shows that, in general, the two types of perturbations couple to each other. This is an outline of a possible procedure to study nonlinear and non-Gaussian effects during multifield inflation.