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arXiv 0709.1400gr-qc
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暗能量是暗能量抵消的遗迹?

Dark Energy as a Relic of the Vacuum-Energy Cancellation?

O. M. Lecian, G. Montani

摘要:

我们分析了各向同性FRW宇宙中引力场的指数拉格朗日密度的动力学含义。然后,我们讨论了广义deSitter相位的特点,预测的新的弗里德曼方程。只有当真空-能量密度与理论基本长度之比具有一个诱人的负特征时,才出现一致的deSitter解。这种选择使我们能够解释目前的宇宙暗能量作为真空能量抵消的遗迹,由于宇宙学常数内在地包含在我们的计划。相应的标量-张量描述的模型也解决了,和标量场的行为进行了分析的宇宙学项的负值和正值。在第一种情况下,弗里德曼方程在真空和存在外部物质的情况下进行了研究,而在第二种情况下,量子机制是在引力相互作用的“排斥”性质的框架内进行的,正如最近几期《圈量子宇宙学》中所描述的那样。特别是,在真空的情况下,我们发现一个纯粹的非爱因斯坦效应,根据负的宇宙学常数提供了一个加速deSitter动力学,在该地区的指数项的级数展开不成立。

英文摘要:

We analyze the dynamical implications of an exponential Lagrangian density for the gravitational field, as referred to an isotropic FRW Universe. Then, we discuss the features of the generalized deSitter phase, predicted by the new Friedmann equation. The existence of a consistent deSitter solution arises only if the ratio between the vacuum-energy density and that associated with the fundamental length of the theory acquires a tantalizing negative character. This choice allows us to explain the present universe dark energy as a relic of the vacuum-energy cancellation due to the cosmological constant intrinsically contained in our scheme. The corresponding scalar-tensor description of the model is addressed too, and the behavior of the scalar field is analyzed for both negative and positive values of the cosmological term. In the first case, the Friedmann equation is studied both in vacuum and in presence of external matter, while, in the second case, the quantum regime is approached in the framework of ''repulsive'' properties of the gravitational interaction, as described in recent issues in Loop Quantum Cosmology. In particular, in the vacuum case, we find a pure non-Einsteinian effect, according to which a negative cosmological constant provides an accelerating deSitter dynamics, in the region where the series expansion of the exponential term does not hold.

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