Anomaly Mediation from Unbroken Supergravity

TL;DR

This paper explores how anomaly mediation in supergravity leads to soft masses for superpartners, revealing new insights into the role of unbroken SUSY in AdS space and extending the analysis to sfermion masses with all-order calculations.

Contribution

It extends the understanding of anomaly mediation to sfermion masses, clarifies the role of unbroken SUSY in AdS space, and addresses previous misconceptions with gauge-invariant effective actions.

Findings

Anomaly mediation can produce sfermion soft masses even when SUSY appears broken.

The gauge-invariant 1PI effective action contains the expected anomaly-mediated spectrum.

All-order calculations of sfermion spectrum and goldstino couplings consistent with RG invariance.

Abstract

When supergravity (SUGRA) is spontaneously broken, it is well known that anomaly mediation generates sparticle soft masses proportional to the gravitino mass. Recently, we showed that one-loop anomaly-mediated gaugino masses should be associated with unbroken supersymmetry (SUSY). This counterintuitive result arises because the underlying symmetry structure of (broken) SUGRA in flat space is in fact (unbroken) SUSY in anti-de Sitter (AdS) space. When quantum corrections are regulated in a way that preserves SUGRA, the underlying AdS curvature (proportional to the gravitino mass) necessarily appears in the regulated action, yielding soft masses without corresponding goldstino couplings. In this paper, we extend our analysis of anomaly mediation to sfermion soft masses. Already at tree-level we encounter a number of surprises, including the fact that zero soft masses correspond to broken (AdS) SUSY. At one-loop, we explain how anomaly mediation appears when regulating SUGRA in a way that preserves super-Weyl invariance. We find that recent claims in the literature about the non-existence of anomaly mediation were based on a Wilsonian effective action with residual gauge dependence, and the gauge-invariant 1PI effective action contains the expected anomaly-mediated spectrum. Finally, we calculate the sfermion spectrum to all orders, and use supertrace relations to derive the familiar two-loop soft masses from minimal anomaly mediation, as well as unfamiliar tree-level and one-loop goldstino couplings consistent with renormalization group invariance.