Boulware state in exactly solvable models of 2D dilaton gravity

TL;DR

This paper investigates the effects of quantum fields in the Boulware state on 2D dilaton gravity models, revealing conditions under which singularities are smoothed or replaced by regular star-like configurations.

Contribution

It provides exact solutions showing how non-monotonic coupling functions can eliminate classical singularities in 2D dilaton gravity with quantum effects.

Findings

Non-monotonic coupling H(φ) can remove classical singularities.

Regular star-like configurations can form due to quantum backreaction.

Monotonic H(φ) solutions exhibit bouncing points and isotropic singularities.

Abstract

We discuss self-consistent geometries and behavior of dilaton in exactly solvable models of 2D dilaton gravity, with quantum fields in the Boulware state. If the coupling $H(\phi)$ between curvature and dilaton $\phi $ is non-monotonic, backreaction can remove the classical singularity. As a result, an everywhere regular star-like configuration may appear, in which case the Boulware state, contrary to expectations, smooths out the system. For monotonic $H(\phi)$ exact solutions confirm the features found before with the help of numerical methods: the appearance of the bouncing point and the presence of isotropic singularity at the classically forbidden branch of the dilaton.