2004/05/31 by Steven Weinberg · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Solar and Space Plasma Dynamics #astro-ph #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.70.083522
published as Phys.Rev. D70 (2004) 083522 · 12 pages, typographical errors corrected, acknowledgment added. Article accepted for publication in Physical Review D
arxiv created 2004/07/20 · openalex publication_date 2004/10/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Even if nonadiabatic perturbations are generated in multifield inflation, the perturbations will become adiabatic if the Universe after inflation enters an era of local thermal equilibrium, with no nonzero conserved quantities, and will remain adiabatic as long as the wavelength is outside the horizon, even when local thermal equilibrium no longer applies. Small initial nonadiabatic perturbations associated with imperfect local thermal equilibrium remain small when baryons are created from out-of-equilibrium decay of massive particles, or when dark matter particles go out of local thermal equilibrium.