Nonsingular 4d-flat branes in six-dimensional supergravities

TL;DR

This paper demonstrates the existence of nonsingular, flat 4-dimensional brane solutions within six-dimensional supergravity models, revealing new configurations that preserve partial supersymmetry without singularities.

Contribution

It introduces novel nonsingular solutions for flat 4d branes in 6d supergravity with scalar fields on noncompact target spaces, expanding the understanding of brane configurations.

Findings

Nonsingular solutions with positive tension branes are possible.

Scalar field divergences occur without curvature singularities.

Solutions preserve half of the supersymmetry locally.

Abstract

We show that six-dimensional supergravity models admit nonsingular solutions in the presence of flat three-brane sources with positive tensions. The models studied in this paper are nonlinear sigma models with the target spaces of the scalar fields being noncompact manifolds. For the particular solutions of the scalar field equations which we consider, only two brane sources are possible which are positioned at those points where the scalar field densities diverge, without creating a divergence in the Ricci scalar or the total energy. These solutions are locally invariant under 1/2 of D=6 supersymmetries, which, however, do not integrate to global Killing spinors. Other branes can be introduced by hand by allowing for local deficit angles in the transverse space without generating any kind of curvature singularities.