FLRW cosmology in Weyl-Integrable Space-Time
FLRW cosmology in Weyl-Integrable Space-Time
复制标题
外尔可积时空中的 FLRW 宇宙学
DOI：
10.1088/1475-7516/2011/11/051
复制
发表时间：
2012
影响因子：
6.4
通讯作者：
N.Dadhich
中科院分区：
文献类型：
--
作者：
R.Gannouji;H.Nandan;N.Dadhich
本文研究了广义相对论的Weyl时空延拓，通过测地线汇的聚焦和散焦来研究FLRW宇宙学。导出了外尔时空中膨胀、剪切和旋转的演化方程。特别地，我们考虑了爱因斯坦-帕拉蒂尼形式中引力的Starobinsky修正，f（R）= R+ βR 2− 2Λ，它被证明是外尔可积时空（WIST）的一种简化，其中外尔矢量是一个梯度。修正后的Raychaudhuri方程采用Hill型方程的形式，然后分析该方程以研究焦散线的形成。在这个模型中，有可能有一个没有大爆炸奇点的循环宇宙，但不幸的是，周期性非常短。
We investigate the Weyl space-time extension of general relativity (GR) for studying the FLRW cosmology through focusing and defocusing of the geodesic congruences. We have derived the equations of evolution for expansion, shear and rotation in the Weyl space-time. In particular, we consider the Starobinsky modification, f (R)= R+ βR 2− 2Λ, of gravity in the Einstein-Palatini formalism, which turns out to reduce to the Weyl integrable space-time (WIST) with the Weyl vector being a gradient. The modified Raychaudhuri equation takes the form of the Hill-type equation which is then analysed to study the formation of the caustics. In this model, it is possible to have a Big Bang singularity free cyclic Universe but unfortunately the periodicity turns out to be extremely short.