Generalised superconformal higher-spin multiplets

TL;DR

This paper introduces generalized superconformal higher-spin gauge multiplets with various depths, derives their invariant actions in conformally-flat superspaces, and explores their behavior on Bach-flat backgrounds, revealing non-uniqueness issues.

Contribution

It proposes a new class of superconformal higher-spin multiplets with different depths and constructs their invariant actions, extending to Bach-flat backgrounds and analyzing non-gauge multiplets.

Findings

Generalized superconformal higher-spin multiplets are constructed.

Invariant actions are derived for these multiplets on conformally-flat and Bach-flat backgrounds.

Gauge and Weyl invariance do not always uniquely determine models on Bach-flat backgrounds.

Abstract

We propose generalised $\mathcal{N}=1$ superconformal higher-spin (SCHS) gauge multiplets of depth $t$, $\Upsilon_{\alpha(n)\dot{\alpha}(m)}^{(t)}$, with $n\geq m \geq 1$. At the component level, for $t>2$ they contain generalised conformal higher-spin (CHS) gauge fields with depths $t-1$, $t$ and $t+1$. The supermultiplets with $t=1$ and $t=2$ include both ordinary and generalised CHS gauge fields. Super-Weyl and gauge invariant actions describing the dynamics of $\Upsilon_{\alpha(n)\dot{\alpha}(m)}^{(t)}$ on conformally-flat superspace backgrounds are then derived. For the case $n=m=t=1$, corresponding to the maximal-depth conformal graviton supermultiplet, we extend this action to Bach-flat backgrounds. Models for superconformal non-gauge multiplets, which are expected to play an important role in the Bach-flat completions of the models for $\Upsilon^{(t)}_{\alpha(n)\dot{\alpha}(m)}$, are also provided. Finally we show that, on Bach-flat backgrounds, requiring gauge and Weyl invariance does not always determine a model for a CHS field uniquely.