Euclidean wormholes with minimally coupled scalar fields

TL;DR

This paper investigates Euclidean wormholes in Einstein's gravity with minimally coupled scalar fields across various potentials, revealing conditions for their existence and implications for cosmological evolution.

Contribution

It provides a comprehensive analysis of quantum and classical Euclidean wormholes for different scalar potentials, identifying new configurations and their effects on cosmology.

Findings

Hawking and Page wormholes exist for several potentials in both classically allowed and forbidden regions.

Inverse quartic potential admits semiclassical wormhole solutions.

Classical wormholes with finite throats are found for multiple potentials, affecting late-time cosmology.

Abstract

A detailed study of quantum and semiclassical Euclidean wormholes for Einstein's theory with a minimally coupled scalar field has been performed for a class of potentials. Massless, constant, massive (quadratic in the scalar field) and inverse (linear) potentials admit Hawking and Page wormhole boundary condition both in the classically forbidden and allowed regions. Inverse quartic potential has been found to exhibit semiclassical wormhole configuration. Classical wormholes under suitable back-reaction leading to a finite radius of the throat, where strong energy condition is satisfied, have been found for the zero, constant, quadratic and exponential potentials. Treating such classical Euclidean wormholes as initial condition, late stage of cosmological evolution has been found to remain unaltered from standard Friedmann cosmology, except for the constant potential which under back-reaction produces a term like negative cosmological constant.