Parent form for higher spin fields on anti-de Sitter space
Glenn Barnich, Maxim Grigoriev
TL;DR
The paper develops a first-order parent theory for free higher-spin gauge fields on AdS by embedding AdS into a flat space and applying a Fedosov-like BRST construction. It shows how both Fronsdal’s metric-like and Vasiliev’s unfolded descriptions arise as consistent reductions from this parent framework, clarifying the algebraic structure (notably an $sp(4)$-type subalgebra) and enabling intermediate formulations. The approach provides a geometrically transparent setting in which generalized auxiliary fields and Lagrangian formulations can be systematically managed, potentially aiding the compatibility of Lagrangian and interaction structures in higher-spin theory. Overall, the work unifies BRST, embedding-space, and unfolded formalisms into a cohesive, covariant picture with explicit reduction rules to standard and unfolded descriptions on AdS.
Abstract
We construct a first order parent field theory for free higher spin gauge fields on constant curvature spaces. As in the previously considered flat case, both Fronsdal's and Vasiliev's unfolded formulations can be reached by two different straightforward reductions. The parent theory itself is formulated using a higher dimensional embedding space and turns out to be geometrically extremely transparent and free of the intricacies of both of its reductions.
