Consistent gravitino couplings in non-supersymmetric strings

TL;DR

This paper investigates the consistency of gravitino interactions in non-supersymmetric string theories, proposing a form of non-linear local supersymmetry that ensures their viability at low energies.

Contribution

It demonstrates the existence of a non-linearly realized local supersymmetry in non-supersymmetric string models, providing the leading order effective Lagrangian.

Findings

Identification of non-linear supersymmetry in open sectors

Derivation of the low energy effective Lagrangian

Implications for lower-dimensional models

Abstract

The massless spectrum of the ten dimensional USp(32) type I string has an N=1 supergravity multiplet coupled to non-supersymmetric matter. This raises the question of the consistency of the gravitino interactions. We resolve this apparent puzzle by arguing for the existence of a local supersymmetry which is non-linearly realised in the open sector. We determine the leading order low energy effective Lagrangian. Similar results are expected to apply to lower dimensional type I models where supergravity is coupled to non-supersymmetric branes.