Cosmology of the Spinor Emergent Universe and Scale-invariant
  Perturbations
  A nonsingular emergent universe cosmology can be realized by a
nonconventional spinor field as first developed in \cite{Cai:2012yf}. We study
the mechanisms of generating scale-invariant primordial power spectrum of
curvature perturbation in the frame of spinor emergent universe cosmology.
Particularly, we introduce a light scalar field of which the kinetic term
couples to the bilinear of the spinor field. This kinetic coupling can give
rise to an effective "Hubble radius" for primordial fluctuations from the
scalar field to squeeze at large length scales as well as to form a nearly
scale-invariant power spectrum. We study the stability of the backreaction and
constrain the forms of the coupling terms. These almost scale-independent
fluctuations are able to be transferred into curvature perturbation after the
epoch of emergent universe through a generalized curvaton mechanism and thus
can explain cosmological observations.
