Quantum fluctuations and CMB anisotropies in one-bubble open inflation   models
  We first develop a method to calculate a complete set of mode functions which describe the quantum fluctuations generated in one-bubble open inflation models. We consider two classes of models. One is a single scalar field model proposed by Bucher, Goldhaber and Turok and by us as an example of the open inflation scinario, and the other is a two-field model such as the ``supernatural'' inflation proposed by Linde and Mezhlumian. In both cases we assume the difference in the vacuum energy density between inside and outside the bubble is negligible. There are two kinds of mode functions. One kind has usual continuous spectrum and the other has discrete spectrum with characteristic wavelengths exceeding the spatial curvature scale. The latter can be further devided into two classes in terms of its origin. One is called the de Sitter super-curvature mode, which arises due to the global spacetime structure of de Sitter space, and the other is due to fluctuations of the bubble wall. We calculate the spectrum of quantum fluctuations in these models and evaluate the resulting large angular scale CMB anisotropies. We find there are ranges of model parameters that are consistent with observed CMB anisotropies. 
Kazuhiro Yamammoto, Misao Sasaki and Takahiro Tanaka