The Two Faces of Anomaly Mediation

TL;DR

This paper reveals that anomaly mediation in supersymmetry breaking actually comprises two distinct phenomena, gravitino and Kahler mediation, which can be distinguished by their couplings to the goldstino and have different physical origins.

Contribution

The paper identifies and differentiates two phenomena within anomaly mediation, providing a new way to analyze sequestering through goldstino couplings.

Findings

Gravitino mediation generates soft masses without goldstino couplings.

Kahler mediation produces soft masses proportional to beta functions.

Absence of goldstino couplings indicates sequestering in SUSY models.

Abstract

Anomaly mediation is a ubiquitous source of supersymmetry (SUSY) breaking which appears in almost every theory of supergravity. In this paper, we show that anomaly mediation really consists of two physically distinct phenomena, which we dub "gravitino mediation" and "Kahler mediation". Gravitino mediation arises from minimally uplifting SUSY anti-de Sitter (AdS) space to Minkowski space, generating soft masses proportional to the gravitino mass. Kahler mediation arises when visible sector fields have linear couplings to SUSY breaking in the Kahler potential, generating soft masses proportional to beta function coefficients. In the literature, these two phenomena are lumped together under the name "anomaly mediation", but here we demonstrate that they can be physically disentangled by measuring associated couplings to the goldstino. In particular, we use the example of gaugino soft masses to show that gravitino mediation generates soft masses without corresponding goldstino couplings. This result naively violates the goldstino equivalence theorem but is in fact necessary for supercurrent conservation in AdS space. Since gravitino mediation persists even when the visible sector is sequestered from SUSY breaking, we can use the absence of goldstino couplings as an unambiguous definition of sequestering.