2008/10/31 by Tsutomu Kobayashi, Kei-ichi Maeda, Kei Maeda · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Geophysics and Gravity Measurements #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.79.024009
published as Phys.Rev.D79:024009,2009 · 9 pages, 9 figures, v2: minor modifications, version accepted for publication in Phys. Rev. D
openalex publication_date 2009/01/14 · arxiv created 2009/01/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Although f(R) modified gravity models can be made to satisfy solar system and cosmological constraints, it has been shown that they have the serious drawback of the nonexistence of stars with strong gravitational fields. In this paper, we discuss whether or not higher curvature corrections can remedy the nonexistence consistently. The following problems are shown to arise as the costs one must pay for the f(R) models that allow for neutrons stars: (i) the leading correction must be fine-tuned to have the typical energy scale \ensuremathμ\ensuremath\lesssim10^\ensuremath-19 GeV, which essentially comes from the free fall time of a relativistic star; (ii) the leading correction must be further fine-tuned so that it is not given by the quadratic curvature term. The second problem is caused because there appears an intermediate curvature scale, and laboratory experiments of gravity will be under the influence of higher curvature corrections. Our analysis thus implies that it is a challenge to construct viable f(R) models without very careful and unnatural fine-tuning.