论文标题
公制的扭转折双伴侣Chern-simons重力：延迟宇宙学中的重力波
Torsional birefringence in metric-affine Chern-Simons gravity: gravitational waves in late-time cosmology
论文作者
论文摘要
在具有投影性不变性的公制植物Chern-simons重力的背景下，我们在同质和各向同性的宇宙学情况下得出了分析溶液，用于扭转和非中性溶液，并由平坦的Friedmann-Robertson-Walker-Walker-Walker-Walker Metric描述。我们在一些细节中讨论了宇宙解决方案的一般特性，例如完美的流体，例如动态稳定性和大弹跳点的出现，我们研究了某些特定的解决方案的结构，这些解决方案又重现了Sitter and Power Ward行为为量表因子。然后，我们将重点放在DE Sitter场景中的一阶扰动上，并研究了绝热极限中重力波的传播，以查看张量和标量极化。特别是，我们发现公制张量模式与扭转张量成分相对，导致外观，就像在Chern-simons重力的公制版本中一样，双向反发，其特征是左右圆形圆极化状态的分散关系不同。结果，扭转的纯张力部分像波浪一样繁殖，而非对象则像谐波振荡器一样脱离和表现。最后，我们讨论标量模式，概述它们在及时衰减而不传播时概述。
In the context of the metric-affine Chern-Simons gravity endowed with projective invariance, we derive analytical solutions for torsion and nonmetricity in the homogeneous and isotropic cosmological case, described by a flat Friedmann-Robertson-Walker metric. We discuss in some details the general properties of the cosmological solutions in the presence of a perfect fluid, such as the dynamical stability and the emergence of big bounce points, and we examine the structure of some specific solutions reproducing de Sitter and power law behaviours for the scale factor. Then, we focus on first-order perturbations in the de Sitter scenario, and we study the propagation of gravitational waves in the adiabatic limit, looking at tensor and scalar polarizations. In particular, we find that metric tensor modes couple to torsion tensor components, leading to the appearance, as in the metric version of Chern-Simons gravity, of birefringence, characterized by different dispersion relations for the left and right circularized polarization states. As a result, the purely tensor part of torsion propagates like a wave, while nonmetricity decouples and behaves like a harmonic oscillator. Finally, we discuss scalar modes, outlining as they decay exponentially in time and do not propagate.
