Naked singularities in low energy, effective string theory

TL;DR

This paper constructs and analyzes solutions in low energy string theory, revealing the existence of naked singularities that challenge cosmic censorship, and explores duality symmetries and energy condition violations.

Contribution

It presents new solutions derived via duality symmetries in string theory, demonstrating naked singularities that violate cosmic censorship while obeying energy conditions.

Findings

Several solutions possess naked singularities despite obeying energy conditions.

Dual solutions show duality in energy condition violations and conservation.

Some backgrounds serve as counterexamples to cosmic censorship in string theory.

Abstract

Solutions to the equations of motion of the low energy, effective field theory emerging out of compactified heterotic string theory are constructed by making use of the well-known duality symmetries. Beginning with four-dimensional solutions of the Einstein-massless scalar field theory in the canonical frame we first rewrite the corresponding solutions in the string frame. Thereafter, using the T and S duality symmetries of the low energy string effective action we arrive at the corresponding uncharged, electrically charged and magnetically charged solutions. Brief comments on the construction of dual versions of the Kerr-Sen type using the dilatonic Kerr solution as the seed are also included. Thereafter, we verify the status of the energy conditions for the solutions in the string frame. Several of the metrics found here are shown to possess naked singularities although the energy conditions are obeyed. Dual solutions exhibit a duality in the conservation/violation of the Null and Averaged Null Energy Conditions (NEC/ANEC), a fact demonstrated earlier in the context of black holes (hep-th/9604047) and cosmologies (hep-th/9611122). Additionally, those backgrounds which conserve the NEC/ANEC in spite of possesing naked singularities serve as counterexamples to cosmic censorship in the context of low energy, effective string theory.