Rainbow gravity and scale-invariant fluctuations
Rainbow gravity and scale-invariant fluctuations
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DOI：
10.1103/physrevd.88.041303
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发表时间：
2013-07
影响因子：
5
通讯作者：
G. Amelino-Camelia;M. Arzano;Giulia Gubitosi;J. Magueijo
中科院分区：
文献类型：
--
作者：
G. Amelino-Camelia;M. Arzano;Giulia Gubitosi;J. Magueijo
我们重新研究了最近提出的一个场景，其中与光谱维度流相关的变形色散关系到 UV 值 2 导致了宇宙涨落的尺度不变光谱，而不需要暴胀。在这种情况下，假设了爱因斯坦引力。该理论显示了光速与波长相关，但通过转换为合适的“彩虹框架”，可以消除该特征，但代价是改变重力。我们发现随后出现的彩虹引力理论表明，引力在高能量时会关闭（或至少导致普遍的共形耦合）。这解释了为什么波动在所有尺度上都是尺度不变的：不存在这样的水平尺度。对于不会导致精确尺度不变性的色散关系，我们在彩虹框架中发现了深奥的膨胀。我们认为这些结果揭示了降维现象下重力的行为。
We re-examine a recently proposed scenario where the deformed dispersion relations associated with a flow of the spectral dimension to a UV value of 2 leads to a scale-invariant spectrum of cosmological fluctuations, without the need for inflation. In that scenario Einstein gravity was assumed. The theory displays a wavelength-dependent speed of light but by transforming to a suitable "rainbow frame" this feature can be removed, at the expense of modifying gravity. We find that the ensuing rainbow gravity theory is such that gravity switches off at high energy (or at least leads to a universal conformal coupling). This explains why the fluctuations are scale-invariant on all scales: there is no horizon scale as such. For dispersion relations that do not lead to exact scale invariance we find instead esoteric inflation in the rainbow frame. We argue that these results shed light on the behaviour of gravity under the phenomenon of dimensional reduction.