2000/06/30 by D. Boyanovsky, Boyanovsky, D., H. J. de Vega +1 · 1 citation
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Astrophysics (astro-ph) #Condensed Matter (cond-mat) #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph) #Solar and Space Plasma Dynamics #astro-ph #cond-mat #gr-qc #hep-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0006446
Latex file, 60 pages, 14 figures in .eps files. To appear in the Proceedings of the VIIth. Erice Chalonge School on Astrofundamental Physics, N. S'anchez ed., Kluwer, Series C, 2000
arxiv created 2000/06/30 · openalex publication_date 2000/06/30 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The physics during the inflationary stage of the universe is of quantum nature involving extremely high energy densities. Moreover, it is out of equilibrium on a fastly expanding dynamical geometry.We present in these lectures non-perturbative out of equilibrium field theoretical methods in cosmological universes. We then study the non-linear dynamics of quantum fields in matter and radiation dominated FRW and de Sitter universes. We investigate the explosive particle production due to spinodal instabilities and parametric amplification in FRW and deSitter universes with and without symmetry breaking. We show how the particle production is sensitive to the expansion of the universe.We present a complete renormalization scheme for the equation of motion and the energy momentum tensor in flat cosmologies. We then consider an O(N) inflaton model coupled self-consistently to gravity in the semiclassical approximation, with `new inflation' type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. We find that spinodal instabilities drive the growth of non-perturbatively large quantum fluctuations which shut off the inflationary growth of the scale factor. A very specific combination of these large quantum fluctuations plus the inflaton zero mode assemble into a new effective field. This new field behaves classically and it is the object which actually rolls down. The metric perturbations during inflation are computed using this effective field and the Bardeen variable for superhorizon modes during inflation. We compute the amplitude and index for the spectrum of scalar density and tensorperturbations and find for these models that the spinodal instabilities are responsible for a `red' primordial spectrum.