Non-singular bounce scenarios in loop quantum cosmology and the
  effective field description
  A non-singular bouncing cosmology is generically obtained in loop quantum
cosmology due to non-perturbative quantum gravity effects. A similar picture
can be achieved in standard general relativity in the presence of a scalar
field with a non-standard kinetic term such that at high energy densities the
field evolves into a ghost condensate and causes a non-singular bounce. During
the bouncing phase, the perturbations can be stabilized by introducing a
Horndeski operator. Taking the matter content to be a dust field and an
ekpyrotic scalar field, we compare the dynamics in loop quantum cosmology and
in a non-singular bouncing effective field model with a non-standard kinetic
term at both the background and perturbative levels. We find that these two
settings share many important properties, including the result that they both
generate scale-invariant scalar perturbations. This shows that some quantum
gravity effects of the very early universe may be mimicked by effective field
models.
