The dual graviton in duality covariant theories

TL;DR

This paper discusses the dual graviton problem within duality covariant theories of M-theory, highlighting how additional compensator fields enable consistent formulations and their role in compactifications.

Contribution

It reviews and elaborates on constructing consistent dual graviton theories using compensator fields to maintain gauge invariance and on-shell equivalence.

Findings

Constructed consistent dual graviton theories with compensator fields.

Demonstrated the role of these fields in generalized Scherk-Schwarz compactifications.

Showed the importance of compensator fields in Kaluza-Klein truncations.

Abstract

We review (and elaborate on) the `dual graviton problem' in the context of duality covariant formulations of M-theory (exceptional field theories). These theories require fields that are interpreted as components of the dual graviton in order to build complete multiplets under the exceptional groups E$_{d(d)}$, $d=2,\ldots, 9$. Circumventing no-go arguments, consistent theories for such fields have been constructed by incorporating additional covariant compensator fields. The latter fields are needed for gauge invariance but also for on-shell equivalence with $D=11$ and type IIB supergravity. Moreover, these fields play a non-trivial role in generalized Scherk-Schwarz compactifications, as for instance in consistent Kaluza-Klein truncation on AdS$_4\times {\rm S}^7$.