arXiv 1906.044252019-06-11gr-qc

6D广义Randall-Sundrum模型中4-膜的各向异性演化

Anisotropic evolution of 4-brane in a 6D generalized Randall-Sundrum model

Guang-Zhen Kang, De-Sheng Zhang, Long Du, Jun Xu, Hong-Shi Zong

备注：: 7 pages, 1 figure
DOI：: 10.1088/1674-1137/43/9/095101

摘要：

本文研究了具有体宇宙学常数的6维广义Randall-Sundrum膜世界。结果表明，膜上的每个应力-能量张量$T_{ab}^{i}$近似于一个恒定的真空能量。这与Randall-Sundrum模型一致，在该模型中，每个3-膜拉格朗日量分离出一个恒定的真空能量。通过采用各向异性度规，我们得到了5维Friedmann-Robertson-Walker场方程。在稍晚的时期，宇宙的膨胀与$t^{\frac{1}{2}}$成正比，这与辐射主导的时期相似。我们还研究了两个$a(t)$和两个$b(t)$的情况。在$t$的大范围内，我们得到了与积分常数无关的3d有效宇宙学常数$Λ_{eff}=-2Ω/3>0$.这里的尺度因子是指数膨胀，这与我们目前对宇宙的观察是一致的。我们的结果表明，有可能构建一个模型，解决了暗能量的问题，同时保证一个积极的膜张力。

英文摘要：

We investigate a 6d generalized Randall-Sundrum brane world scenario with a bulk cosmological constant. It is shown that each stress-energy tensor $T_{ab}^{i}$ on the brane is similar to a constant vacuum energy. This is consistent with the Randall-Sundrum model in which each 3-brane Lagrangian separated out a constant vacuum energy. By adopting an anisotropic metric ansatz, we obtain the 5d Friedmann-Robertson-Walker field equations. At a little later period, the expansion of the universe is proportional to $t^{\frac{1}{2}}$ which is as similar as the period of the radiation-dominated. We also investigate the case with two $a(t)$ and two $b(t)$. In a large region of $t$, we obtain the 3d effective cosmological constant $Λ_{eff}=-2Ω/3>0$ which is independent of the integral constant. Here the scale factor is exponential expansion which is consistent with our present observation of the universe. Our results demonstrate that it is possible to construct a model which solves the dark energy problem, meanwhile guaranteeing a positive brane tension.

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