تقرير
Isotropic universe with almost scale-invariant fourth-order gravity
| العنوان: | Isotropic universe with almost scale-invariant fourth-order gravity |
|---|---|
| المؤلفون: | Schmidt, H. -J., Singleton, D. |
| المصدر: | J.Math.Phys. 54 (2013) 062502 |
| سنة النشر: | 2012 |
| المجموعة: | Astrophysics General Relativity and Quantum Cosmology |
| مصطلحات موضوعية: | General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Extragalactic Astrophysics, 83F05, 83D05, 83C15, 53Z05, 85A40 |
| الوصف: | We study a broad class of isotropic vacuum cosmologies in fourth-order gravity under the condition that the gravitational Lagrangian be scale-invariant or almost scale-invariant. The gravitational Lagrangians considered will be of the form L = f(R) + k(G) where R and G are the Ricci and Gauss-Bonnet scalars respectively. Specifically we take f(R) = R^2n and k(G) = G^n or k(G) = G ln G. We find solutions in closed form for a spatially flat Friedmann space-time and interpret their asymptotic early-time and late-time behaviour as well as their inflationary stages. One unique example which we discuss is the case of a very small negative value of the parameter b in the Lagrangian L = R^2 + b G ln G which leads to the replacement of the exact de Sitter solution from L = R^2 (being a local attractor) to a power-law inflation exact solution also representing a local attractor. This shows how one can modify the dynamics from de Sitter to power-law inflation by the addition of the G ln G-term. Comment: several revisions included, 28 pages, J. Math. Phys. accepted |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1063/1.4808255 |
| URL الوصول: | http://arxiv.org/abs/1212.1769 |
| رقم الأكسشن: | edsarx.1212.1769 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1063/1.4808255 |
|---|