2026/03/31 by Anonymous, Yupeng Zhang, Shuxun Tian +1
Computer Science · Physics and Astronomy · #Computability, Logic, AI Algorithms #Distributed systems and fault tolerance #Optimization and Search Problems #astro-ph.CO
paper · pdf · doi:10.1103/d2xt-vpnz
published as Phys. Rev. D 114, 023565 (2026) · 7 pages, 2 figures, published in Phys. Rev. D
openalex publication_date 2026/07/09 · openalex created_date 2026/07/10 · arxiv created 2026/07/30 · arxiv updated 2026/07/31 · openalex updated_date 2026/07/31
We study whether an open FLRW universe with a negative cosmological constant can evade the eventual recollapse characteristic of an AdS-type universe. Within a power-law realization of Fab-Four theory, we solve the background equations numerically and analyze the asymptotic dynamics. For the representative branch and parameter choice studied here, we find that the scalar sector provides a self-tuning-like compensation for the negative Λ, while the curvature term remains unscreened. As a result, the universe can continue expanding instead of recollapsing. Instead, the universe evolves toward a curvature-dominated linear-expansion regime, a ∝ t. To probe the underlying compensation mechanism, we further analyze an auxiliary zero-curvature subsystem using Poincaré compactification. In the Λ<0 domain, there exist background trajectories that approach a critical point at infinity. Near this point, the compensating scalar-Λ sector becomes stiff-like, wϕ+Λ → 1, so that the system effective energy density redshifts faster than curvature (wk = -1/3). Although this auxiliary analysis does not cover the full curved cosmology, it is consistent with and qualitatively supports the numerical finding that the net ϕ+Λ contribution becomes subdominant to curvature, thereby preventing recollapse despite Λ<0. This extends the application of the self-tuning mechanism to the AdS region and offers a possibility for the AdS Universe predicted by string theory to become a reality.