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 consider cosmological inflationary models in which vector fields play somerole in the generation of the primordial curvature perturbation $\zeta$. Suchmodels are interesting because the involved vector fields naturally seedstatistical anisotropy in the primordial fluctuations which could eventuallyleave a measurable imprint on the cosmic microwave background fluctuations. Inthis article, we estimate the scale and shape dependent effects on thenon-Gaussianity (NG) parameters due to the scale dependent statisticalanisotropy in the distribution of the fluctuations. For concreteness, we use apower spectrum (PS) of the fluctuations of the quadrupolar form:$P_\zeta(\vec{k})\equiv P_\zeta(k)[1+g_\zeta(k)(\hat{n} \cdot \hat{k})^2 ]$,where $g_{\zeta}(k)$ is the only quantity which parametrizes the level ofstatistical anisotropy and $\hat{n}$ is a unitary vector which points towardsthe preferred direction. Then, we evaluate the contribution of the running of$g_{\zeta}(k)$ on the NG parameters by means of the $\delta N$ formalism. Wefocus specifically on the details for the $f_{\rm NL}$ NG parameter, associatedwith the bispectrum $B_\zeta$, but the structure of higher order NG parametersis straightforward to generalize. Although the level of statistical anisotropyin the PS is severely constrained by recent observations, the importance ofstatistical anisotropy signals in higher order correlators remains to bedetermined, this being the main task that we address here. The precisemeasurement of the shape and scale dependence (or running) of statisticalparameters such as the NG parameters and the statistical anisotropy level couldprovide relevant elements for model building and for the determination of thepresence (or nonpresence) of inflationary vector fields and their role in theinflationary mechanism.

Scale and shape dependent non-Gaussianity in the presence of inflationary vector fields