Higgs and super-Higgs effects with naturally vanishing vacuum energy

TL;DR

This paper develops N=1 supergravity models where both gauge symmetry and supersymmetry are spontaneously broken with zero classical vacuum energy, highlighting the importance of correctly analyzing the super-Higgs effect in such scenarios.

Contribution

It introduces models with simultaneous gauge and supersymmetry breaking, maintaining vanishing vacuum energy, and emphasizes the significance of proper effective theory analysis for super-Higgs phenomena.

Findings

Gauge symmetry and supersymmetry are both spontaneously broken with zero vacuum energy.

Naive integration out of heavy degrees of freedom can miss key features of the super-Higgs effect.

Potential relevance to grand-unified theories and string constructions.

Abstract

We construct $N=1$ supergravity models where the gauge symmetry and supersymmetry are both spontaneously broken, with naturally vanishing classical vacuum energy and unsuppressed Goldstino components along gauge non-singlet directions. We discuss some physically interesting situations where such a mechanism could play a role, and identify the breaking of a grand-unified gauge group as the most likely possibility. We show that, even when the gravitino mass is much smaller than the scale $m_X$ of gauge symmetry breaking, important features can be missed if we first naively integrate out the degrees of freedom of mass ${\cal O} (m_X)$, in the limit of unbroken supersymmetry, and then describe the super-Higgs effect in the resulting effective theory. We also comment on possible connections with extended supergravities and realistic four-dimensional string constructions.