Quantum tunneling in the early universe

早期宇宙中的量子隧道效应，如膨胀宇宙中的真空相变，与当今宇宙的大尺度结构密切相关。在这个项目中，我们系统地发展了一种方法来分析早期宇宙中的隧道现象，考虑到宇宙学的内在环境，特别是关于膨胀宇宙，我们成功地获得了描述德西特背景中的假真空的模函数。然后我们发现，为了正确地描述真空气泡中的量子态，必须包括一组通常意义上不可归一化的模(双曲空间上的所谓超曲率模)。我们分析了气泡壁涨落对超曲率扰动的影响，结合这些结果，我们提出了一种新的宇宙膨胀模型：单泡开放膨胀宇宙情景。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，我们研究了由这些量子涨落引起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。我们发现，我们的新设想是一个可行的设想，可以成功地解释目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.