Comments on Anomaly Cancellations by Pole Subtractions and Ghost Instabilities with Gravity

TL;DR

This paper examines the role of anomaly pole subtraction in supersymmetric theories coupled to gravity, highlighting potential issues with unitarity and infrared instabilities caused by ghost condensations.

Contribution

It provides a detailed analysis of anomaly cancellation mechanisms via pole subtraction in superspace and discusses their implications for unitarity and consistency in supergravity.

Findings

Anomaly pole subtraction can be necessary for unitarization.

Ghost condensation may lead to infrared instabilities.

Superanomaly multiplet subtraction has limited physical significance.

Abstract

We investigate some aspects of anomaly cancellation realized by the subtraction of an anomaly pole, stressing on some of its properties in superspace. In a local formulation these subtractions can be described in terms of a physical scalar, an axion and related ghosts. They appear to be necessary for the unitarization of the theory in the ultraviolet, but they may generate an infrared instability of the corresponding effective action, signalled by ghost condensation. In particular the subtraction of the superanomaly multiplet by a pole in superspace is of dubious significance, due to the different nature of the chiral and conformal anomalies. In turn, this may set more stringent constraints on the coupling of supersymmetric theories to gravity.