Creation of the universe with a stealth scalar field

TL;DR

This paper investigates how stealth scalar fields, which do not affect spacetime geometry, influence the quantum creation probability of the de Sitter universe, revealing conditions under which their effects are significant or comparable to trivial fields.

Contribution

It demonstrates that stealth scalar fields can significantly impact universe creation probabilities and identifies specific conditions for their effects to be comparable to trivial fields.

Findings

Creation with a stealth field is possible for discrete coupling constants.

The creation probability with a stealth field is always less than or comparable to that with a trivial field.

Stealth fields can have a significant or nearly equivalent effect depending on parameters.

Abstract

The stealth scalar field is a non-trivial configuration without any back-reaction to geometry, which is characteristic for non-minimally coupled scalar fields. Studying the creation probability of the de Sitter universe with a stealth scalar field by the Hartle and Hawking's semi-classical method, we show that the effect of the stealth field can be significant. For the class of scalar fields we consider, creation with a stealth field is possible for a discrete value of the coupling constant and its creation probability is always less than that with a trivial scalar field. However, those creation rates can be almost the same depending on the parameters of the theory.