Stochastic emergence of inflaton fluctuations in a SdS primordial universe with large-scale repulsive gravity from a 5D vacuum

TL;DR

This paper introduces a stochastic method to analyze inflaton fluctuations in an early universe with a black hole, showing that fluctuations depend on black hole mass and are not perfectly scale-invariant.

Contribution

It develops a novel stochastic framework for inflaton fluctuations in a 4D SdS universe derived from a 5D vacuum, linking black hole mass to fluctuation characteristics.

Findings

Inflaton fluctuations are sensitive to black hole mass.

Fluctuations are not exactly scale-independent at the end of inflation.

The approach connects higher-dimensional vacuum metrics to observable inflationary features.

Abstract

We develop a stochastic approach to study scalar field fluctuations of the inflaton field in an early inflationary universe with a black-hole (BH), which is described by an effective 4D SdS metric. Considering a 5D Ricci-flat SdS static metric, we implement a planar coordinate transformation, in order to obtain a 5D cosmological metric, from which the effective 4D SdS metric can be induced on a 4D hypersurface. We found that at the end of inflation, the squared fluctuations of the inflaton field are not exactly scale independent and becomes sensitive with the mass of the BH.