Symmetron宇宙学中的引力波双折射
Gravitational Wave Birefringence in Symmetron Cosmology
AI总结：
本文提出一种Z₂不变但显式破缺宇称的symmetron类Chern-Simons引力耦合，证明其可导致引力波振幅双折射，并利用LIGO-Virgo-Kagra数据约束耦合参数。
摘要：
symmetron是一种轻标量场，它提供了一种屏蔽机制，以规避来自局部引力测试的严格约束。为实现这一目标，symmetron模型被赋予Z₂对称性。本文引入了一种新的symmetron类Chern-Simons引力相互作用，该相互作用在Z₂变换下不变，但显式破缺宇称对称性。结果发现，当引力波（GW）在symmetron背景上传播时，这种耦合能够产生引力波振幅双折射。由于物质密度差异，symmetron场分布在进入星系时会发生显著变化，因此需要分别讨论河外和星系内情形。一方面，宇宙学symmetron场遵循绝热解，这会诱导出破缺宇称的引力波振幅修正，其指数与引力波频率和传播距离成正比。另一方面，在银河系内symmetron采取屏蔽解，所产生的引力波双折射仅为引力波频率的函数。通过进一步比较这两种贡献，我们发现河外symmetron场产生主导性的双折射效应。最后，利用来自LIGO-Virgo-Kagra的最新引力波数据，我们对该symmetron模型中的破缺宇称耦合参数给出了合理约束。
英文摘要：
The symmetron is a light scalar which provides a screening mechanism so as to evade the strong constraints from local gravity tests. In order to achieve this goal, a $Z_2$ symmetry is imposed on the symmetron model. In this paper, we introduce a new symmetron Chern-Simons-like gravitational interaction which is $Z_2$ invariant but breaks the parity symmetry explicitly. As a result, it is found that this coupling can generate gravitational wave (GW) amplitude birefringence when GWs propagate over the symmetron backgrounds. Due to the matter density difference, the symmetron profile changes significantly when entering the galaxy, so that we need to discuss the extra-galactic and galactic situations separately. On the one hand, the cosmological symmetron field follows the adiabatic solution, which induces a parity-violating GW amplitude correction with its exponent proportional to the GW frequency and the traveling distance. On the other hand, the symmetron takes the screening solution within the Milky Way, and the generated GW birefringence is only a function of the GW frequency. By further comparing these two contributions, we find that the extra-galactic symmetron field produces the dominant birefringence effects. Finally, with the latest GW data from LIGO-Virgo-Kagra, we place a reasonable constraint on the parity-violating coupling parameter in this symmetron model.
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