Non-linear Realizations and Higher Curvature Supergravity

TL;DR

This paper explores non-linear realizations of local supersymmetry in supergravity using constrained superfields, introducing new constraints and couplings that lead to ghost-free higher curvature models and novel scalar degrees of freedom.

Contribution

It introduces new constraints affecting curvature multiplets and higher derivative interactions, including a constraint that removes a massive gravitino and couples the goldstino to the super Gauss--Bonnet multiplet.

Findings

New constraints remove massive gravitino in supergravity.

Construction of ghost-free higher curvature supergravities.

Emergence of a new scalar degree of freedom from coupling to super Gauss--Bonnet.

Abstract

We focus on non-linear realizations of local supersymmetry as obtained by using constrained superfields in supergravity. New constraints, beyond those of rigid supersymmetry, are obtained whenever curvature multiplets are affected as well as higher derivative interactions are introduced. In particular, a new constraint, which removes a very massive gravitino is introduced, and in the rigid limit it merely reduces to an explicit supersymmetry breaking. Higher curvature supergravities free of ghosts and instabilities are also obtained in this way. Finally, we consider direct coupling of the goldstino multiplet to the super Gauss--Bonnet multiplet and discuss the emergence of a new scalar degree of freedom.