Existence and bounds of nonlinear singularity-free cosmological solutions in a string-inspired gravity

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Hauptverfasser: He, Chihang, Liu, Chao
Format: Preprint
Veröffentlicht: 2025
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author He, Chihang
Liu, Chao
author_facet He, Chihang
Liu, Chao
contents We provide a rigorous proof for the existence of homogeneous, isotropic and globally singularity-free cosmological solutions in Einstein-dilaton-Gauss-Bonnet (EdGB) gravity with exponential coupling. While numerical studies suggested such solutions exist, a formal proof remained elusive. By employing a novel ``power identity method'' and overcoming significant challenges posed by the strong nonlinearities of the exponential coupling, which are not present in the quadratic coupling analyzed in our companion paper \cite{he2025proofssingularityfreesolutionsscalarization}, we establish a FLRW solution valid for all time $t\in(-\infty,+\infty)$, where the Hubble parameter remains positive and vanishes asymptotically, while the scalar field evolves monotonically. This result align with numerical simulations and offer a firm mathematical foundation for singularity-free cosmology in a string-inspired setting.
format Preprint
id arxiv_https___arxiv_org_abs_2512_00455
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Existence and bounds of nonlinear singularity-free cosmological solutions in a string-inspired gravity
He, Chihang
Liu, Chao
Analysis of PDEs
General Relativity and Quantum Cosmology
We provide a rigorous proof for the existence of homogeneous, isotropic and globally singularity-free cosmological solutions in Einstein-dilaton-Gauss-Bonnet (EdGB) gravity with exponential coupling. While numerical studies suggested such solutions exist, a formal proof remained elusive. By employing a novel ``power identity method'' and overcoming significant challenges posed by the strong nonlinearities of the exponential coupling, which are not present in the quadratic coupling analyzed in our companion paper \cite{he2025proofssingularityfreesolutionsscalarization}, we establish a FLRW solution valid for all time $t\in(-\infty,+\infty)$, where the Hubble parameter remains positive and vanishes asymptotically, while the scalar field evolves monotonically. This result align with numerical simulations and offer a firm mathematical foundation for singularity-free cosmology in a string-inspired setting.
title Existence and bounds of nonlinear singularity-free cosmological solutions in a string-inspired gravity
topic Analysis of PDEs
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2512.00455