Stability of cosmological singularity-free solutions in quadratic gravity

Asorey, Manuel (Universidad de Zaragoza) ; Ezquerro, Fernando (Universidad de Zaragoza) ; Pardina, Miguel (Universidad de Zaragoza)

Resumen: We introduce a large family of homogeneous and isotropic cosmological solutions in quadratic gravity which are singularity-free at early and late times. This kind of smooth solutions only emerge beyond the nonstandard de Sitter branch 3⁢ <, and being the couplings of the 2 and −2 ⁢ terms. We have analyzed the stability of these singularity-free solutions by computing the second-order variation of the action. We show that the expected instability is similar to that of the standard Λ Cold Dark Matter (Λ CDM) scenario. Thus, they provide cosmological background scenarios as legitimate as that of the Standard Model. The complete analysis shows that a singular big bang scenario can emerge from a singularity-free cosmological scenario when the parameters of the theory are slightly modified, which provides a bridge between the two very different cosmological scenarios with similar instabilities.

Idioma: Inglés

DOI: 10.1103/PhysRevD.111.064020

Año: 2025

Publicado en: Physical Review D 111, 6 (2025), 9 pp.
ISSN: 2470-0010

Financiación: info:eu-repo/grantAgreement/ES/DGA-FSE/E21-17R
Financiación: info:eu-repo/grantAgreement/ES/DGIID-DGA/2020-E21-17R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PGC2022-126078NB-C21
Financiación: info:eu-repo/grantAgreement/ES/NextGenerationEU/PRTR

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Física Teórica (Dpto. Física Teórica)