Conformal frames and D-dimensional gravity

TL;DR

This paper reviews static, spherically symmetric solutions in multidimensional gravity theories, exploring their causal structures, black hole and wormhole solutions, and observational predictions, with a focus on the role of conformal frames.

Contribution

It provides a comprehensive analysis of solutions in scalar-tensor and string-inspired multidimensional gravity models, emphasizing the importance of conformal frames for observational comparisons.

Findings

Existence of black holes, wormholes, and particle-like solutions in these theories.

Observational predictions such as post-Newtonian coefficients and Coulomb law violations.

Conformal frames significantly affect the interpretation of physical results.

Abstract

We review some results concerning the properties of static, spherically symmetric solutions of multidimensional theories of gravity: various scalar-tensor theories and a generalized string-motivated model with multiple scalar fields and fields of antisymmetric forms associated with p-branes. A Kaluza-Klein type framework is used: there is no dependence on internal coordinates but multiple internal factor spaces are admitted. We discuss the causal structure and the existence of black holes, wormholes and particle-like configurations in the case of scalar vacuum with arbitrary potentials as well as some observational predictions for exactly solvable systems with p-branes: post-Newtonian coefficients, Coulomb law violation and black hole temperatures. Particular attention is paid to conformal frames in which the theory is initially formulated and which are used for its comparison with observations; it is stressed that, in general, these two kinds of frames do not coincide.