Stability of cosmological singularity-free solutions in quadratic gravity

2024/12/13 by Asorey, M., Ezquerro, F., Pardina, M.
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th)

paper · doi:10.48550/arxiv.2412.10111

Abstract

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 emerges beyond the unstable de Sitter branch 3α< β, α being the coupling of the R² term and -β the coupling of the R_μν² term. We have analyzed the stability of these singularity-free solutions by computing the second-order variation of the action. The complete analysis shows that a Big Bang can emerge from a singularity-free regime when the parameters of the theory are slightly modified, revealing the unstable nature of this type of solutions.

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• Effect of R² on the stability of de Sitter solution of the generalized Einsteinian cubic gravity

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