Vacua in locally de Sitter cosmologies, and how to distinguish them

Toussaint, Vladimir; Louko, Jorma

Abstract

(1 + 1)-dimensional locally de Sitter–Friedmann-Robertson-Walker cosmologies with compact spatial sections allow cosh, sinh, and exponential evolution laws, each with a freely specifiable spatial circumference parameter, and the value of this parameter has an invariant geometric meaning for the cosh and sinh evolution laws. We identify geometrically preferred states for a quantized massive scalar field on these cosmologies, some singled out by adiabatic criteria in the distant past, with an ambiguity remaining due to a massive zero mode, and others induced from the Euclidean vacuum on standard (1 + 1)-dimensional de Sitter space by a quotient construction. We show that a comoving quantum observer, modelled as an Unruh-DeWitt detector, can distinguish these states from the Euclidean vacuum on standard de Sitter space. Numerical plots are given in selected parameter regimes. We also evaluate the field’s stress-energy tensor expectation value for those states that are induced from the Euclidean vacuum by a quotient construction.

Citation

Toussaint, V., & Louko, J. (2024). Vacua in locally de Sitter cosmologies, and how to distinguish them. Physical Review D, 109(2), Article 025007. https://doi.org/10.1103/physrevd.109.025007

• Journal Article Type: Article
• Acceptance Date: Aug 29, 2023
• Online Publication Date: Jan 17, 2024
• Publication Date: Jan 17, 2024
• Deposit Date: Jan 18, 2024
• Publicly Available Date: Jan 18, 2024
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 109
• Issue: 2
• Article Number: 025007
• DOI: https://doi.org/10.1103/physrevd.109.025007
• Keywords: Quantum fields in curved spacetime
• Public URL: https://nottingham-repository.worktribe.com/output/29836854
• Publisher URL: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.109.025007