Duality and Spontaneously Broken Supergravity in Flat Backgrounds

TL;DR

This paper explores how the super Higgs mechanism in models with zero cosmological constant involves gauging flat groups within the duality group, with the structure depending on whether gravitinos are BPS saturated or in long multiplets.

Contribution

It demonstrates the connection between super Higgs mechanism, flat group gaugings, and the nature of gravitino multiplets in various supersymmetry breaking scenarios.

Findings

BPS saturated gravitinos imply non-abelian flat groups.

Long multiplet gravitinos allow for abelian flat groups.

Models include Scherk-Schwarz breaking and string compactifications with fluxes.

Abstract

It is shown that the super Higgs mechanism that occurs in a wide class of models with vanishing cosmological constant (at the classical level) is obtained by the gauging of a flat group which must be an electric subgroup of the duality group. If the residual massive gravitinos which occur in the partial supersymmetry breaking are BPS saturated, then the flat group is non abelian. This is so for all the models obtained by a Scherk-Schwarz supersymmetry breaking mechanism. If gravitinos occur in long multiplets, then the flat groups may be abelian. This is the case of supersymmetry breaking by string compactifications on an orientifold T^6/Z_2 with non trivial brane fluxes.