Global and local properties of AdS(2) higher spin gravity
K. B. Alkalaev
TL;DR
This work constructs and analyzes a two-dimensional BF theory with an infinite tower of higher spin fields as a consistent $AdS_{2}$ higher spin gravity, clarifying both frame-like and metric-like formulations. Central to the approach is an unfolded, cohomological framework built from two nilpotent operators $\sigma_{\pm}$, which yield dual metric-like theories and reveal how massive-scalar and conserved-current sectors arise in the one-form, and how Weyl tensors organize the zero-form sector. The authors realize the higher spin algebras via an $o(2,1)$–$sp(2)$ Howe duality, presenting oscillator constructions, trace decompositions, and a taxonomy of quotient algebras (horizontal, vertical, and double factorizations) including the well-known hs$[ u]$ family. They then extend to a non-linear BF action valued in these quotient algebras and analyze linearization around $AdS_{2}$, showing how reduced models emerge and how the parent action links to dual metric-like formulations. The results illuminate how 2d higher spin gravity can couple topological gauge fields and dilatons in a controlled, algebraically rich setting, with potential implications for boundary dynamics and higher-dimensional extensions.
Abstract
Two-dimensional BF theory with infinitely many higher spin fields is proposed. It is interpreted as the AdS(2) higher spin gravity model describing a consistent interaction between local fields in AdS(2) space including gravitational field, higher spin partially-massless fields, and dilaton fields. We carry out analysis of the frame-like and the metric-like formulation of the theory. Infinite-dimensional higher spin global algebras and their finite-dimensional truncations are realized in terms of o(2,1) - sp(2) Howe dual auxiliary variables.
