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arXiv 1202.2328gr-qc
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弯曲乘积时空中的粒子运动与扰动动力系统

Particle Motion and Perturbed Dynamical System in Warped Product Spacetimes

Pinaki Bhattacharya, Sarbari Guha

摘要:

本文用动力系统分析方法研究了具有类空动态额外维的弯曲积时空形式的五维宇宙的动力学。我们分解了测地线方程,得到了沿额外维度的运动,并研究了当爱因斯坦张量的交叉对角元素为零时,以及当它是非零时,相关的动力系统。在第一种情况下,引入能量函数的概念沿相路径的额外的维坐标,我们已经研究了能量函数如何依赖于翘曲因子。能量函数被用来衡量膜位移引起的微扰量。在几何上,膜位移的效应表现为沿着额外维度的坐标平移,从而在靠近膜的区域产生沿着额外维度的测地线运动的变化。然后我们研究了在常规度量扰动下的测地线运动,包括位似运动和共形运动,并考察了Mashhoon-Wesson型度量的临界点的性质。最后我们研究了零测地线和类时测地线在Einstein张量的交叉对角元不为零的条件下的运动,并考察了扰动对动力系统临界点的影响。

英文摘要:

In this paper we have used the dynamical systems analysis to study the dynamics of a five-dimensional universe in the form of a warped product spacetime with a spacelike dynamic extra dimension. We have decomposed the geodesic equations to get the motion along the extra dimension and have studied the associated dynamical system when the cross-diagonal element of the Einstein tensor vanishes, and also when it is non-vanishing. In the first case, introducing the concept of an energy function along the phase path in terms of the extra-dimensional coordinate, we have examined how the energy function depends on the warp factor. The energy function has been used as a measure of the amount of perturbation caused by a brane displacement. Geometrically the effect of brane displacement is manifested in terms of a coordinate translation along the extra dimension, thereby producing a change in the geodesic motion along the extra dimension in the region close to the brane. Then we studied the geodesic motion under a conventional metric perturbation in the form of homothetic motion and conformal motion and examined the nature of critical points for a Mashhoon-Wesson-type metric. Finally we investigated the motion for null and timelike geodesics under the condition when the cross-diagonal element of the Einstein tensor is non-vanishing and examined the effects of perturbation on the critical points of the dynamical system.

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