We examine the role of consistency with causality and quantum mechanics in determining the properties of gravitation. We begin by examining two different classes of interacting theories of massless spin 2 particles -- gravitons. One involves coupling the graviton with the lowest number of derivatives to matter, the other involves coupling the graviton with higher derivatives to matter, making use of the linearized Riemann tensor. The first class requires an infinite tower of terms for consistency, which is known to lead uniquely to general relativity. The second class only requires a finite number of terms for consistency, which appears as another class of theories of massless spin 2. We recap the causal consistency of general relativity and show how this fails in the second class for the special case of coupling to photons, exploiting related calculations in the literature. In a companion paper [1] this result is generalized to a much broader set of theories. Then, as a causal modification of general relativity, we add light scalar particles and recap the generic violation of universal free-fall they introduce and its quantum resolution. This leads to a discussion of a special type of scalar-tensor theory; the $F(\mathcal{R})$ models. We show that, unlike general relativity, these models do not possess the requisite counterterms to be consistent quantum effective field theories. Together this helps to remove some of the central assumptions made in deriving general relativity.
Gravitational Faraday rotation, gravitational spin Hall effect, and spin-refined causality analysis from Magnusian matrix in effective field theories of gravity
Consistency between causality and complementarity guaranteed by the Robertson inequality in quantum field theory
关于引力是否应该量子化的争论由来已久。最近，作者在[Sci。Rep. 6，22777（2016）; Proc. Natl. Acad. Sci. U.S.A. 106，3035（2009）]讨论了涉及质量/带电体量子叠加的Gedanken实验中因果关系和互补性之间的不一致性，Belenchia等人[Phys. Rev. D 98，126009（2018）; Int. J. Mod. Phys. D 28，1943001（2019）]通过要求引力/电磁场的量子辐射和真空涨落解决了不一致性。受他们工作的启发，我们根据量子场论重新分析了因果性和互补性这两种物理性质之间的一致性。在这个分析中，我们考虑一个Gedanken实验的启发[科学。Rep. 6，22777（2016）; Proc. Natl. Acad. Sci. U.S.A. 106，3035（2009）; Phys. Rev. D 98，126009（2018）; Int. J. Mod. Phys. D 28，1943001（2019）]，其中与光子场耦合的两个带电粒子处于两个轨迹的叠加中。首先，我们观察到，因果关系是由光子场的延迟传播满足。其次，通过引入可见度和路径信息之间的不等式，我们证明了光子场的量子辐射和真空涨落确保了互补性。我们进一步发现，与光子场相关的Robertson不等式导致了Gedanken实验中因果性和互补…
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）
Consistency analysis of a CPT-even and CPT-odd lorentz-violating effective field theory in the electrodynamics at Planck scale by an influence of a background isotropic field
William H. Miller III Department of Physics & Astronomy, Johns Hopkins University（约翰斯·霍普金斯大学）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（塔塔基础研究所国际理论科学中心）；Chennai Mathematical institute（金奈数学研究所）；Indian Institute of Technology, Gandhinagar（印度理工学院甘地纳格尔分校）
A Proposed Test of the Local Causality of Spacetime
一个支配时空中度规场和物质场的理论是{ \it local causal}，如果任何区域中场的概率分布完全由该区域过去的物理数据决定，也就是说，它与类空分离点上的事件无关。广义相对论显然是局部因果的，因为一个区域中的场完全由其过去的物理数据决定。人们自然会问，在其他可能的理论中，时空的基本描述是经典的和几何的--例如，将经典时空几何随机耦合到物质的量子场论的假设理论--是否也可能是局部因果的。另一方面，引力的量子理论应该允许在宏观水平上违反局域因果关系的时空的创造。本文描述了一个实验来检验时空的局域因果关系，从而检验引力是否像引力的量子理论所建议的那样在这方面表现。这个实验要么直接证明引力场不是局部因果的，从而证明量子引力是弱的;要么为量子理论的有效性确定一个明确的界限。
