Bubble nucleation and inflationary perturbations
  In this work we study the imprints of bubble nucleation on primordial
inflationary perturbations. We assume that the bubble is formed via the
tunneling of a spectator field from the false vacuum of its potential to its
true vacuum. We consider the configuration in which the observable CMB sphere
is initially outside of the bubble. As the bubble expands, more and more
regions of the exterior false vacuum, including our CMB sphere, fall into the
interior of the bubble. The modes which leave the horizon during inflation at
the time when the bubble wall collides with the observable CMB sphere are
affected the most. The bubble wall induces non-trivial anisotropic and scale
dependent corrections in the two point function of the curvature perturbation.
The corrections in the curvature perturbation and the diagonal and off-diagonal
elements of CMB power spectrum are estimated.
