Backreactions are considered in a de Sitter spacetime whose cosmological constant is
generated by the potential of a scalar field. The leading order gravitational effect of nonlinear …

Linearized fluctuations of quantized matter fields and the spacetime geometry around de
Sitter space are considered in the case that the matter fields are conformally invariant …

We study the backreaction on the mean field geometry due to a non-conformal quantum field
in a Robertson–Walker background. In the regime of small mass and small deviation from …

Our present understanding of cosmology assumes that the universe underwent a short
period of accelerated expansion known as inflation [1–5]. The inflationary scenario has been …

We consider the effect of inhomogeneities on the expansion of the Einstein–de Sitter
universe. We find that the back-reaction of linear scalar metric perturbations results in …

Starting from the equation of motion of the quantum operator of a real scalar field φ in de
Sitter space–time, a simple differential equation is derived which describes the evolution of …

A spatially flat Robertson-Walker spacetime driven by a cosmological constant is
nonconformally coupled to a massless scalar field. The equations of semiclassical gravity …

We consider the linearized semiclassical Einstein equations for small deviations around de
Sitter spacetime including the vacuum polarization effects of conformal fields. Employing the …

Eternal inflation is shown to require violations of the Null Energy Condition (NEC) on
superhorizon scales. With light scalar fields as the matter sources in a de Sitter background …

We treat a model in which tensor perturbations of de Sitter spacetime, represented as a
spatially flat model, are modified by the effects of the vacuum fluctuations of a massless …