CMB in open inflation

The possibility to have an infinite open inflationary universe inside a bubble of a finite size is one of the most interesting realizations extensively discussed in the literature. The original idea was based on the theory of tunneling and bubble formation in the theories of a single scalar field. However, for a long time we did not have any consistent models of this type, so it was impossible to compare predictions of such models with the observational data on the CMB anisotropy. The first semi-realistic model of this type was proposed only very recently [A. Linde, Phys. Rev. D 59, 023503 (1999)]. Here we present the results of our investigation of the scalar and tensor perturbation spectra and the resulting CMB anisotropy in such models. In all models which we have studied there are no supercurvature perturbations. The spectrum of scalar CMB anisotropies has a minimum at small $l$ and a plateau at $l=O\left(10\right)\mathrm{}$ for low ${\Omega }_0.$ Meanwhile tensor CMB anisotropies are peaked at $l=2.\mathrm{}$ The relative magnitude of the scalar CMB spectra versus tensor CMB spectra at small $l$ depends on the parameters of the models.