Answers are grounded in this paper and cite their sources.
Taking clues from the recent construction of the covariant action for type II and heterotic string field theories, we construct a manifestly Lorentz covariant action for type IIB supergravity, and discuss its gauge fixing maintaining manifest Lorentz invariance. The action contains a (non-gravitating) free 4-form field besides the usual fields of type IIB supergravity. This free field, being completely decoupled from the interacting sector, has no physical consequence.
No takes yet. Share an insight, caveat, or question.
A 2016 study studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: