English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present a mechanism to transfer the spectrum of perturbations in a scalarisocurvature field $\xi$ onto the matter content in the radiation era viamodulated, instant preheating after ekpyrosis. In this setup, $\xi$ determinesthe coupling constant relevant for the decay of a preheat matter field intoFermions. The resulting power spectrum is scale invariant if $\xi$ remainsclose to a scaling solution in new ekpyrotic models of the universe; byconstruction the spectrum is independent of the detailed physics near thebounce. The process differs from the curvaton mechanism, which has been usedrecently to revive the ekpyrotic scenario, in that no peculiar behavior of$\xi$ shortly before or during the bounce is needed. In addition, a concreteand efficient realization of reheating after ekpyrosis is provided; thismechanism is not tied to ekpyrotic models, but could equally well be used inother setups, for instance inflationary ones. We estimate non-Gaussianities andfind no additional contributions in the most simple realizations, in contrastto models using the curvaton mechanism.

Modulated Perturbations from Instant Preheating after new Ekpyrosis