Nonsingular ekpyrotic/cyclic model in loop quantum cosmology
Nonsingular ekpyrotic/cyclic model in loop quantum cosmology
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DOI：
10.1103/physrevd.80.124013
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发表时间：
2009-07
影响因子：
5
通讯作者：
T. Cailleteau;Parampreet Singh;K. Vandersloot
中科院分区：
文献类型：
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作者：
T. Cailleteau;Parampreet Singh;K. Vandersloot
我们研究了非微扰量子引力效应的作用在ekpyrotic/cyclic模型中使用的有效框架圈量子宇宙学中存在的各向异性。我们表明，量子几何修改的普朗克尺度附近的动力学方程中理解的Bianchi-I时空在圈量子宇宙学的量子化，导致经典奇异性的决议，并导致在宇宙的非奇异过渡从收缩到膨胀的分支。在普朗克体系中，宇宙经历多次小的反弹，各向异性剪切在整个演化过程中保持有界。一个新的功能，这是缺乏各向同性模型，是一个自然的转折点的模量场从负区域的潜在的循环现象，如在原来的范式设想。我们的工作表明，在ekpyrotic/cyclic模型中引入量子引力效应可能会导致一个可行的方案，而不会违反零能量条件。
We study the role of nonperturbative quantum gravity effects in the ekpyrotic/cyclic model using the effective framework of loop quantum cosmology in the presence of anisotropies. We show that quantum geometric modifications to the dynamical equations near the Planck scale as understood in the quantization of Bianchi-I spacetime in loop quantum cosmology lead to the resolution of classical singularity and result in a nonsingular transition of the Universe from the contracting to the expanding branch. In the Planck regime, the Universe undergoes multiple small bounces and the anisotropic shear remains bounded throughout the evolution. A novel feature, which is absent for isotropic models, is a natural turn-around of the moduli field from the negative region of the potential leading to a cyclic phenomena as envisioned in the original paradigm. Our work suggests that incorporation of quantum gravitational effects in the ekpyrotic/cyclic model may lead to a viable scenario without any violation of the null energy condition.