1202.4453 (Raquel H. Ribeiro)

Inflationary signatures of single-field models beyond slow-roll    [PDF]

Raquel H. Ribeiro

If the expansion of the early Universe was not purely de Sitter, the
statistical imprints of the primordial density perturbation on the cosmic
microwave background can be quite different from those following slow-roll
inflation. In this paper we study the inflationary signatures of all
single-field models not plagued by ghost-like instabilities. We assume small
deviations from exact scale-invariance, as supported by current cosmological
constraints, allow for a rapid change of the Hubble parameter and the phase
speed of scalar fluctuations. We obtain the propagator of scalar fluctuations
and compute the bispectrum, keeping next-order corrections proportional to the
deviation of the spectral index from unity. These theories offer an explicit
example where the shape and scale dependences of the bispectrum are highly
non-trivial for reasonable breaking of slow-roll.

View original: http://arxiv.org/abs/1202.4453