Open hybrid inflation

We propose an open hybrid inflation scenario that produces an open universewith a `tilted' n>1 spectrum of metric perturbations. The model contains asymmetry breaking field that tunnels to its true vacuum, producing a singlebubble inside which hybrid inflation drives the universe to almost flatness. Inorder to obtain density perturbations with n > 1 we use the recently proposednew version of hybrid inflation scenario called tilted hybrid inflation. Inthis scenario, unlike in the previously known versions of hybrid inflation, aconsiderable tilt of the spectrum can be obtained without fine-tuning. Thestage of inflation in this model is rather short, which allows us to obtain aninflationary universe with Omega < 1 in a more natural way. We study theseparate contribution of scalar perturbations coming from the continuumsubcurvature modes, the discrete supercurvature mode and the bubble wall modeto the angular power spectrum of temperature fluctuations in open inflation. Wederive bounds on the parameters of the model so that the predicted spectrum iscompatible with the observed anisotropy of the microwave background.Comment: 9 pages, 6 figures, ReVTe