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 address the question of how one can modify the inflationary tensorspectrum without changing at all the successful predictions on the curvatureperturbation. We show that this is indeed possible, and determine the twoquadratic curvature corrections that are free from instabilities and affectonly the tensor sector at the level of linear cosmological perturbations. Bothof the two corrections can reduce the tensor amplitude, though one of themgenerates large non-Gaussianity of the curvature perturbation. It turns outthat the other one corresponds to so-called Lorentz-violating Weyl gravity. Inthis latter case one can obtain as small as 65% of the standard tensoramplitude. Utilizing this effect we demonstrate that even power-law inflationcan be within the 2$\sigma$ contour of the Planck results.

Suppressing the primordial tensor amplitude without changing the scalar sector in quadratic curvature gravity