The no-boundary measure in scalar-tensor gravity

Understand

In this article, we study the no-boundary wave function in scalar-tensor gravity with various potentials for the non-minimally coupled scalar field.

• Our goal is to calculate probabilities for the scalar field - and hence the effective gravitational coupling and cosmological constant - to take specific values.
• Most calculations are done in the minisuperspace approximation, and we use a saddle point approximation for the Euclidean action, which is then evaluated numerically.
• We find that for potentials that have several minima, none of them is substantially preferred by the quantum mechanical probabilities.