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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We study primordial perturbations generated from quantum fluctuations of aninflaton based on the formalism of stochastic gravity. Integrating out thedegree of freedom of the inflaton field, we analyze the time evolution of thecorrelation function of the curvature perturbation at tree level and compare itwith the prediction made by the gauge-invariant linear perturbation theory. Wefind that our result coincides with that of the gauge-invariant perturbationtheory if the e-folding from the horizon crossing time is smaller than somecritical value ($\sim |$slow-roll parameter $|^{-1}$), which is the case forthe scales of the observed cosmological structures. However, in the limit ofthe superhorizon scale, we find a discrepancy in the curvature perturbation,which suggests that we should include the longitudinal part of thegravitational field in the quantization of a scalar field even in stochasticgravity.

Cosmological Density Fluctuations in Stochastic Gravity -- Formalism and Linear Analysis --