论文标题
空间协变性重力中的极化原始重力波
Polarized primordial gravitational waves in spatial covariant gravities
论文作者
论文摘要
空间协变性重力提供了一种自然的方式，可以将奇数空间衍生物项纳入重力作用，从而破坏了引力部门的平等对称性。许多均衡标量调整理论可以通过施加统一仪表来映射到空间协变量框架。这为我们提供了一个通用框架，用于探索原始引力波（PGWS）中的均衡侵略效应。本文的主要目的是研究PGW在空间协变量中的极化及其可能的观察效应。为此，我们首先使用均匀的渐近近似值，首先构建了在慢速通胀期间PGWS模式函数的近似分析解决方案。使用近似解决方案，我们通过分析中的PGWS明确计算功率谱和相应的圆极化。结果表明，来自空间协变量重力对功率谱的新贡献包含两个部分，一个是含价术语的术语，另一个来自奇偶校验术语。虽然既定术语只能影响PGW的总体幅度，但均衡术语诱导PGWS的非零圆极化，即，GWS的左手和右侧极化模式具有不同的振幅。还简要讨论了这种非零圆极化的观察意义。
The spatial covariant gravities provide a natural way to including odd-order spatial derivative terms into the gravitational action, which breaks the parity symmetry at gravitational sector. A lot of parity-violating scalar-tensor theories can be mapped to the spatial covariant framework by imposing the unitary gauge. This provides us with a general framework for exploring the parity-violating effects in primordial gravitational waves (PGWs). The main purpose of this paper is to investigate the polarization of PGWs in the spatial covariant gravities and their possible observational effects. To this end, we first construct the approximate analytical solution to the mode function of the PGWs during the slow-roll inflation by using the uniform asymptotic approximation. With the approximate solution, we calculate explicitly the power spectrum and the corresponding circular polarization of the PGWs analytically. It is shown that the new contributions to power spectrum from spatial covariant gravities contain two parts, one from the parity-preserving terms and the other from the parity-violating terms. While the parity-preserving terms can only affect the overall amplitudes of PGWs, the parity-violating terms induce nonzero circular polarization of PGWs, i.e., the left-hand and right-hand polarization modes of GWs have different amplitudes. The observational implications of this nonzero circular polarization is also briefly discussed.
