Higher-Spin Geometry and String Theory
  The theory of freely-propagating massless higher spins is usually formulated via gauge fields and parameters subject to trace constraints. We summarize a proposal allowing to forego them by introducing only a pair of additional fields in the Lagrangians. In this setting, external currents satisfy usual Noether-like conservation laws, the field equations can be nicely related to those emerging from Open String Field Theory in the low-tension limit, and if the additional fields are eliminated without reintroducing the constraints a geometric, non-local description of the theory manifests itself. 
D. Francia (AEI Institute and Roma Tre) and A. Sagnotti (CERN and   Scuola Normale Superiore)