Quantum tunneling in the early universe

早期宇宙中的量子隧穿现象，如暴胀宇宙中的真空相变，与当前宇宙的大尺度结构有着密切的关系。在这个项目中，我们系统地开发了一种方法来分析早期宇宙中的隧道现象，考虑到宇宙学固有的环境。特别是对于暴胀宇宙，我们成功地获得了描述德西特背景下假真空的模态函数。然后我们发现，为了正确地描述真空泡内的量子态，必须包含一组通常意义上不可归一化的模式（所谓的双曲空间上的超曲率模式）。我们分析了气泡壁波动的影响，气泡壁波动也会引起超曲率扰动。结合这些结果，我们提出了一个新的宇宙暴胀模型；一个泡沫膨胀的宇宙场景。考虑到上述模式以及通常的连续模式对真空泡内量子态的影响，我们研究了由于这些量子涨落而预测的宇宙微波背景辐射的大角度各向异性，并给出了理论模型的约束条件。我们发现我们的新设想是可行的，它可以成功地解释当前宇宙的大尺度结构。

Quantum tunneling in the early universe such as vacuum phase transition in the inflationary universe is deeply related to the large scale structure of the present universe. In this project, we systematically developed the method to analyze tunneling phenomena in the early universe, taking account of environments that are intrinsic to cosmology.In particular, in connection with the inflationary universe, we succeeded in obtaining the mode functions which describe the false vacuum in the de Sitter background. We then discovered that in order to correctly describe the quantum state inside a vacuum bubble, one must include a set of modes which are not normalizable in the usual sense (the so-called supercurvature modes on hyperbolic space). We have analyzed the effect of the bubble wall fluctuations which also give rise to supercurvature perturbations.Combining these results, we proposed a new inflationary model of the universe ; one-bubble open inflationary universe scenario. Taking account of the effect of the modes described above, as well as the usual continuous modes, on the quantum state inside a vacuum bubble, we investigated the predicted large angle anisotropies of the cosmic microwave background radiation due to these quantum fluctuations and gave constraints to theoretical models. We found our new scenario is a viable one that can successfully explain the large scale structure of the present universe.