Forces between stable non-BPS branes

TL;DR

This paper investigates the interactions between non-BPS branes in string theory, revealing a critical separation where the force vanishes and discussing potential generalizations for stable configurations.

Contribution

It constructs a dyonic generalization of non-BPS branes and analyzes their interaction forces, identifying an unstable equilibrium point and proposing ways to achieve stability.

Findings

Force vanishes at a nontrivial critical separation

Branes coalesce into a dyonic state at smaller separations

Potential generalizations may lead to stable minima

Abstract

As a step toward constructing realistic brane world models in string theory, we consider the interactions of a pair of non-BPS branes. We construct a dyonic generalization of the non-BPS branes first constructed by Bergman, Gaberdiel and Sen as orbifolds of D-branes on $T^4/\BZ_2$. The force between a dyonic brane and an electric brane is computed and is found to vanish at a nontrivial critical separation. This equilibrium point is unstable. For smaller separations the branes coalesce to form a composite dyonic state, while for larger separations the branes run off to infinity. We suggest generalizations that will lead to potentials with stable local minima.