We propose that several of the anomalies that have been observed at large angular scales in the CMB have a common origin in a cosmic bounce that took place before the inflationary era. The bounce introduces a new physical scale in the problem, which breaks the almost scale invariance of inflation. As a result, the state of scalar perturbations at the onset of inflation is no longer the Bunch-Davies vacuum, but it rather contains excitations and non-Gaussianity, which are larger for infrared modes. We argue that the combined effect of these excitations and the correlations between CMB modes and longer wavelength perturbations, can account for the observed power suppression, for the dipolar asymmetry, and it can also produce a preference for odd-parity correlations. The model can also alleviate the tension in the lensing amplitude $A_L$. We adopt a phenomenological viewpoint by characterizing the model with a few free parameters, rather than restricting to specific bouncing theories. We identify the minimum set of ingredients needed for our ideas to hold, and point out examples of theories in the literature where these conditions are met.

中文翻译：

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CMB 中的大规模异常和弹跳宇宙学中的非高斯性

我们提出，在 CMB 中在大角度尺度上观察到的一些异常现象的共同起源是在暴胀时代之前发生的宇宙反弹。反弹在问题中引入了新的物理尺度，打破了通货膨胀的几乎尺度不变性。因此，暴胀开始时的标量扰动状态不再是 Bunch-Davies 真空，而是包含激发和非高斯性，这对于红外模式来说更大。我们认为，这些激发的组合效应以及 CMB 模式与较长波长扰动之间的相关性可以解释观察到的功率抑制、偶极不对称性，并且还可以产生对奇偶校验相关性的偏好。该模型还可以减轻透镜振幅 $A_L$ 中的张力。我们采用现象学观点，通过用一些自由参数来表征模型，而不是局限于特定的弹跳理论。我们确定了我们的想法保持所需的最少成分集，并指出文献中满足这些条件的理论示例。