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arXiv 2003.07454hep-th
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关于渐近安全背后量子几何的刻画

On characterizing the Quantum Geometry underlying Asymptotic Safety

Aleksandr Kurov, Frank Saueressig

AI总结:

本文利用有效平均作用的复合算符形式主义,刻画渐近安全纲领中Reuter不动点的量子几何,建立几何算符反常维度与稳定性矩阵的关系,分析其本征值谱并揭示高阶曲率项对预测能力的关键作用。

摘要:

渐近安全纲领建立在基于Reuter不动点的引力高能完备化之上,Reuter不动点是引力重整化群流的一个非平庸不动点。在该不动点处,耦合常数的正则质量维度被量子涨落诱导的反常维度平衡,使得理论在紫外区域具有量子标度不变性。量子涨落的关键作用表明,与该不动点相关的几何呈现非流形性质。本文中,我们利用基于有效平均作用的复合算符形式主义继续刻画这种几何。具体而言,我们给出了d维球面背景上几何算符的反常维度与编码不动点附近线性化重整化群流的稳定性矩阵之间的关系。我们详细分析了稳定性矩阵的本征值谱,并识别出一个“微扰区”,其中谱性质由正则幂次计数主导。我们的结果重现了量子引力涨落将(经典边际的)R²算符转变为相关算符的特征。此外,我们发现两点函数中存在的高阶曲率项在保证Reuter不动点的预测能力方面起着关键作用的强烈迹象。

英文摘要:

The asymptotic safety program builds on a high-energy completion of gravity based on the Reuter fixed point, a non-trivial fixed point of the gravitational renormalization group flow. At this fixed point the canonical mass-dimension of coupling constants is balanced by anomalous dimensions induced by quantum fluctuations such that the theory enjoys quantum scale invariance in the ultraviolet. The crucial role played by the quantum fluctuations suggests that the geometry associated with the fixed point exhibits non-manifold like properties. In this work, we continue the characterization of this geometry employing the composite operator formalism based on the effective average action. Explicitly, we give a relation between the anomalous dimensions of geometric operators on a background $d$-sphere and the stability matrix encoding the linearized renormalization group flow in the vicinity of the fixed point. The eigenvalue spectrum of the stability matrix is analyzed in detail and we identify a "perturbative regime" where the spectral properties are governed by canonical power counting. Our results recover the feature that quantum gravity fluctuations turn the (classically marginal) $R^2$-operator into a relevant one. Moreover, we find strong indications that higher-order curvature terms present in the two-point function play a crucial role in guaranteeing the predictive power of the Reuter fixed point.

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