Publications (2)0 Total impact
ABSTRACT: We consider the linearized semiclassical Einstein equations for small
deviations around de Sitter spacetime including the vacuum polarization effects
of conformal fields. Employing the method of order reduction, we find the exact
solutions for general metric perturbations (of scalar, vector and tensor type).
Our exact (nonperturbative) solutions show clearly that in this case de Sitter
is stable with respect to small metric deviations and a late-time attractor.
Furthermore, they also reveal a breakdown of perturbative solutions for a
sufficiently long evolution inside the horizon. Our results are valid for any
conformal theory, even self-interacting ones with arbitrarily strong coupling.
ABSTRACT: The two-point function for tensor metric perturbations around de Sitter
spacetime including one-loop corrections from massless conformally coupled
scalar fields is calculated exactly. We work in the Poincar\'e patch (with
spatially flat sections) and employ dimensional regularization for the
renormalization process. Unlike previous studies we obtain the result for
arbitrary time separations rather than just equal times. Moreover, in contrast
to existing results for tensor perturbations, ours is manifestly invariant with
respect to the subgroup of de Sitter isometries corresponding to a simultaneous
time translation and rescaling of the spatial coordinates. Having selected the
right initial state for the interacting theory via an appropriate i\epsilon
prescription is crucial for that. Finally, we show that although the two-point
function is a well-defined spacetime distribution, the equal-time limit of its
spatial Fourier transform is divergent. Therefore, contrary to the well-defined
distribution for arbitrary time separations, the power spectrum is strictly
speaking ill-defined when loop corrections are included.