论文标题

四维量子重力的有效自旋泡沫模型

Effective Spin Foam Models for Four-Dimensional Quantum Gravity

论文作者

Asante, Seth K., Dittrich, Bianca, Haggard, Hal M.

论文摘要

多种四维量子重力的方法,例如环量子重力和全息图作为其基本变量。但是,这种运动学的选择很容易导致引力动力学在平坦的空间上达到峰值。我们表明,这是由于如何通过离散的自旋泡沫模型将区域粘在重力路径积分中。我们介绍了一个“有效”旋转泡沫模型的家族,该模型结合了量子区域频谱,尽可能强烈地施加粘合约束,并利用离散的一般相对性动作来指定振幅。这些有效的自旋泡沫模型避免了参数空间的受限态度的平坦度。更简单的有效自旋泡沫模型将有助于数值研究以及对粗透明和重新规定的研究。

A number of approaches to four-dimensional quantum gravity, such as loop quantum gravity and holography, situate areas as their fundamental variables. However, this choice of kinematics can easily lead to gravitational dynamics peaked on flat spacetimes. We show that this is due to how regions are glued in the gravitational path integral via a discrete spin foam model. We introduce a family of `effective' spin foam models that incorporate a quantum area spectrum, impose gluing constraints as strongly as possible, and leverage the discrete general relativity action to specify amplitudes. These effective spin foam models avoid flatness in a restricted regime of the parameter space. The simpler effective spin foam models will be useful for numerical studies and in the investigation of coarse graining and renormalization.

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