Singularities in Low Energy $d = 4$ Heterotic String and Brans-Dicke Theories

TL;DR

This paper explores static, spherically symmetric solutions in low energy four-dimensional heterotic string theory, revealing singular objects with naked singularities and infinite Hawking temperature, and discusses implications for Brans-Dicke theory.

Contribution

It generalizes Schwarzschild solutions in string theory, analyzes singularities and thermodynamics, and connects findings to Brans-Dicke theory and cosmic censorship.

Findings

Solutions exhibit naked singularities when Robertson parameter ≠ 1

Objects have infinite Hawking temperature

Brans-Dicke theory also predicts naked singularities

Abstract

We present the static, spherically symmetric solutions of the low energy $d = 4$ string. They form a simple generalisation of the Schwarzschild solution and describe the gravitational field of a spherical star in perturbative string theory. If the Robertson parameter $\gamma$ is different from one, these solutions describe singular objects with naked singularities at their horizons, and whose Hawking temperature is infinite. These objects might represent ``massive remnants'', the end states of black holes. Our analysis also implies that Brans-Dicke theory has a naked singularity. Invoking cosmic censorship conjecture will rule out Brans-Dicke theory.