Structural Origin of the Gravitino Mass Term: Geometric and Supergravity Perspectives

TL;DR

This paper identifies a minimal superspace projector that isolates the gravitino mass term in four-dimensional N=1 supergravity, providing a geometric and algebraic understanding of its universal structure independent of specific mechanisms.

Contribution

It introduces a unique superspace projector that selects the gravitino mass bilinear, clarifying its geometric origin and universality in supergravity theories.

Findings

The projector isolates the gravitino mass bilinear in superspace.

It extends to N>1 supergravity theories.

The construction is independent of supersymmetry breaking or matter couplings.

Abstract

We identify a minimal superspace projector that uniquely selects the Rarita Schwinger mass bilinear in four-dimensional N=1 supergravity. Working in a reduced superspace with a single fermionic direction, we show that Berezin projection of a canonical even supergeometric form isolates the unique Lorentz-invariant fermionic bilinear compatible with local supersymmetry. The construction is predynamical: it fixes the algebraic structure of the gravitino mass term independently of supersymmetry breaking mechanisms, background geometry, or matter couplings. We show that this projector embeds consistently into curved superspace, extends to N>1 theories, and clarifies the universality of the gravitino mass structure in supergravity.