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arXiv 1706.07421gr-qchep-th
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在非线性状态下修正广义相对论的扩展

Fixing extensions to General Relativity in the non-linear regime

Juan Cayuso, Néstor Ortiz, Luis Lehner

摘要:

什么样的引力理论能够取代广义相对论,这个问题几十年来一直是理论物理学的核心。宇宙学、量子引力和唯象学角度激发了许多不同的替代方案,这些替代方案都经过了来自宇宙学、太阳系和脉冲星观测的检验,通常局限于线性化的范围。来自致密双星的引力波提供了在强引力/高动力学领域探索这些理论的新机会。然而,为此目的,需要对这种制度的动态有可靠的了解。不幸的是,这些理论中的大多数未能定义良好的初始值问题,这阻碍了在表面价值迎接这样的挑战。在这项工作中,我们引入了一个一致的程序能够纠正这种情况。这个程序的灵感来自于Israel和Stewart在70年代后期提出的“固定”粘性相对论流体动力学的方法。我们说明了如何实施这种方法来控制重力理论中高阶导数的不良影响,并讨论了修改后的系统如何仍然捕捉到3+1维中假定的基础理论的真实动态。我们在两个有效的引力理论中勾勒出这个想法的实现,一个在非对易几何的背景下,一个在陈-西蒙斯修正的广义相对论的背景下。

英文摘要:

The question of what gravitational theory could supersede General Relativity has been central in theoretical physics for decades. Many disparate alternatives have been proposed motivated by cosmology, quantum gravity and phenomenological angles, and have been subjected to tests derived from cosmological, solar system and pulsar observations typically restricted to linearized regimes. Gravitational waves from compact binaries provide new opportunities to probe these theories in the strongly gravitating/highly dynamical regimes. To this end however, a reliable understanding of the dynamics in such a regime is required. Unfortunately, most of these theories fail to define well posed initial value problems, which prevents at face value from meeting such challenge. In this work, we introduce a consistent program able to remedy this situation. This program is inspired in the approach to "fixing" viscous relativistic hydrodynamics introduced by Israel and Stewart in the late 70's. We illustrate how to implement this approach to control undesirable effects of higher order derivatives in gravity theories and argue how the modified system still captures the true dynamics of the putative underlying theories in 3+1 dimensions. We sketch the implementation of this idea in a couple of effective theories of gravity, one in the context of Non-commutative geometry, and one in the context of Chern-Simons modified General Relativity.

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