2022/04/11 by Pau Beltrán-Palau, Beltrán-Palau, Pau, Sergi Nadal-Gisbert +5
Physics and Astronomy · #Astrophysics and Star Formation Studies #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #gr-qc
paper · pdf · doi:10.48550/arxiv.2204.05404
11 pages
arxiv created 2022/04/11 · openalex publication_date 2022/04/11 · arxiv updated 2022/04/13 · openalex created_date 2022/04/20 · openalex updated_date 2026/07/28
Vacuum and particles can be naturally defined in the adiabatic regime of an expanding universe. In general, however, there is no preferred choice of a vacuum state, unless the spacetime background possesses special symmetries. In the absence of symmetries the standard viewpoint is to construct distinguished adiabatic states permitting renormalizability of the stress-energy tensor. We study a special non-adiabatic vacuum for a massive scalar field in a radiation-dominated universe defined by imposing early-times conformal symmetry. We show that this state is consistent with renormalization, despite its ultraviolet behaviour is not the conventional one due to the emergence of oscillatory terms.