Scalar fluctuations of the scalar metric during inflation from a
  non-perturbative 5D large-scale repulsive gravity model
  We develop a non-perturbative formalism for scalar metric fluctuations from a
5D extended version of general relativity in vacuum. In this work we
concentrate our efforts on calculations valid on large cosmological scales,
which are the dominant during the inflationary phase of the universe. The
resulting metric in this limit is obtained after implementing a planar
coordinate transformation on a 5D Ricci-flat metric solution. We calculate the
spectrum of these fluctuations with an effective 4D Schwarzschild-de Sitter
spacetime on cosmological scales, which is obtained after we make a static
foliation on the non-compact extra coordinate. Our results show how the squared
metric fluctuations of the primordial universe become scale invariant with the
inflationary expansion.
