D-brane Models with Non-Linear Supersymmetry

TL;DR

This paper explores type I string models where supersymmetry is non-linearly realized on D-branes with broken bulk supersymmetry, analyzing their effective field theory and four-fermion couplings.

Contribution

It introduces a class of models with non-linear supersymmetry on D-branes and studies their effective field theory and phenomenological features.

Findings

Supersymmetry is non-linearly realized on D-branes despite a non-supersymmetric spectrum.

Models can host 3-branes with gauge groups and chiral fermions.

Computed four-fermion couplings of Goldstino with matter fermions.

Abstract

We study a class of type I string models with supersymmetry broken on the world-volume of some D-branes and vanishing tree-level potential. Despite the non-supersymmetric spectrum, supersymmetry is non-linearly realized on these D-branes, while it is spontaneously broken in the bulk by Scherk-Schwarz boundary conditions. These models can easily accommodate 3-branes with interesting gauge groups and chiral fermions. We also study the effective field theory and in particular we compute the four-fermion couplings of the localized Goldstino with the matter fermions on the brane.