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arXiv 2203.08003hep-thgr-qc
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渐近安全de Sitter空间的谱几何

The Spectral Geometry of de Sitter Space in Asymptotic Safety

Renata Ferrero, Martin Reuter

摘要:

利用泛函重整化群方法研究了与背景无关的量子引力,得到了de Sitter解dS ${}_4$的有效几何.调查采用了一种新的方法,其基本成分是一个修改后的谱流的度量依赖的达朗伯,或类似的双曲动力学运营商。相应的单参数谱族和本征函数编码了关于量子时空平均场几何上的动态引力真空涨落的非微扰反作用的信息。作为一种诊断工具,功率的频谱流方法驻留在它的能力,以确定规模依赖的子集的场模式,提供参与的有效场论描述的各个规模的自由度。一个核心的结果是,量子爱因斯坦引力的紫外线包含的有效自由度远远低于背景依赖推理所预测的(错误的)。探索物理场所携带的量子时空的空间几何,我们发现三维空间分裂成一个相干补丁的集合,这些补丁可以单独地,但在整体上不能被沿着重整化群轨迹发生的有效平均作用描述。一个自然的概念,熵的引入,以量化这种碎片化的效果。将张力应用到真实宇宙中,发现了与观测到的宇宙微波背景性质的惊人类比。此外,一组杰出的场模式被发现,在原则上,有能力传输信息的渐近不动点制度从紫外线,几乎整个“规模的历史”,在所观察到的宇宙的宇宙学距离。

英文摘要:

Within the functional renormalization group approach to Background Independent quantum gravity, we explore the scale dependent effective geometry of the de Sitter solution dS${}_4$. The investigation employs a novel approach whose essential ingredient is a modified spectral flow of the metric dependent d'Alembertian, or of similar hyperbolic kinetic operators. The corresponding one-parameter family of spectra and eigenfunctions encodes information about the nonperturbative backreaction of the dynamically gravitating vacuum fluctuations on the mean field geometry of the quantum spacetime. Used as a diagnostic tool, the power of the spectral flow method resides in its ability to identify the scale dependent subsets of field modes that supply the degrees of freedom which participate in the effective field theory description of the respective scale. A central result is that the ultraviolet of Quantum Einstein Gravity comprises far less effective degrees of freedom than predicted (incorrectly) by background dependent reasoning. Exploring the quantum spacetime's spatial geometry carried by physical fields, we find that 3-dimensional space disintegrates into a collection of coherent patches which individually can, but in their entirety cannot be described by one of the effective average actions occurring along the renormalization group trajectory. A natural concept of an entropy is introduced in order to quantify this fragmentation effect. Tentatively applied to the real Universe, surprising analogies to properties of the observed cosmic microwave background are uncovered. Furthermore, a set of distinguished field modes is found which, in principle, has the ability to transport information about the asymptotic fixed point regime from the ultraviolet, across almost the entire "scale history", to cosmological distances in the observed Universe.

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