On higher spins and the tensionless limit of String Theory

TL;DR

This paper explores the spectra of higher-spin fields in the tensionless limit of string theory using BRST formalism, highlighting unconstrained gauge symmetries and their relation to known equations.

Contribution

It introduces simple compensator forms for higher-spin field equations and extends the BRST approach to mixed symmetry and (A)dS backgrounds.

Findings

Unconstrained gauge-invariant formulations for higher-spin fields.

Connection between BRST formalism and Fang-Fronsdal equations.

Extension of higher-spin analysis to (A)dS spaces.

Abstract

We discuss string spectra in the low-tension limit using the BRST formalism, with emphasis on the role of triplets of totally symmetric tensors and spinor-tensors and their generalizations to cases with mixed symmetry and to (A)dS backgrounds. We also present simple compensator forms of the field equations for individual higher-spin gauge fields that display the {unconstrained} gauge symmetry of a previous non-local construction and reduce upon partial gauge fixing to the (Fang-)Fronsdal equations. For Bose fields we also show how a local Lagrangian formulation with {unconstrained} gauge symmetry is determined by a previous BRST construction.