CMB scale dependent non-Gaussianity from massive gravity during inflation
CMB scale dependent non-Gaussianity from massive gravity during inflation
复制标题
DOI：
10.1088/1475-7516/2017/05/034
复制
发表时间：
2017-01
影响因子：
6.4
通讯作者：
Guillem Domènech;T. Hiramatsu;Chunshan Lin;M. Sasaki;M. Shiraishi;Yi Wang
中科院分区：
文献类型：
--
作者：
Guillem Domènech;T. Hiramatsu;Chunshan Lin;M. Sasaki;M. Shiraishi;Yi Wang
我们考虑了膨胀过程中张量模变大的宇宙学模型，并研究了膨胀过程中标量模和大质量张量模混合产生的宇宙微波背景（CMB）温度和偏振双谱。该模型假设在膨胀期间存在一个首选空间框架。局部洛伦兹不变性在宇宙学中已经被打破，因为存在一个优先的静止坐标系。首选空间框架的存在进一步打破了剩余的局部SO(3)不变性，特别是在张量模式中产生了质量。在线性扰动水平上，我们将模型最小化，使矢量模态保持非动态，而标量模态与单场慢滚膨胀中的模态相同。在非线性扰动水平上，这种暴胀的大质量引力子相导致了相当大的标量-标量-张量耦合，比传统情况下的标量-标量-标量耦合大得多。这种标量-标量-张量相互作用在CMB温度和偏振双光谱中留下了尺度依赖的特征。非常有趣的是，我们发现在预测的尺度依赖性和WMAP和普朗克结果中暗示的低多极的尺度依赖性非高斯性之间存在惊人的相似性。
We consider a cosmological model in which the tensor mode becomes massive during inflation, and study the Cosmic Microwave Background (CMB) temperature and polarization bispectra arising from the mixing between the scalar mode and the massive tensor mode during inflation. The model assumes the existence of a preferred spatial frame during inflation. The local Lorentz invariance is already broken in cosmology due to the existence of a preferred rest frame. The existence of a preferred spatial frame further breaks the remaining local SO(3) invariance and in particular gives rise to a mass in the tensor mode. At linear perturbation level, we minimize our model so that the vector mode remains non-dynamical, while the scalar mode is the same as the one in single-field slow-roll inflation. At non-linear perturbation level, this inflationary massive graviton phase leads to a sizeable scalar-scalar-tensor coupling, much greater than the scalar-scalar-scalar one, as opposed to the conventional case. This scalar-scalar-tensor interaction imprints a scale dependent feature in the CMB temperature and polarization bispectra. Very intriguingly, we find a surprizing similarity between the predicted scale dependence and the scale-dependent non-Gaussianities at low multipoles hinted in the WMAP and Planck results.