Dario Francia (Rome & Pisa)
In their simplest form, metric-like Lagrangians for higher-spin massless fields display constrained gauge symmetries, unless auxiliary fields are introduced or locality is foregone. I will show how implementing invariance under divergence-free gauge transformations leads to a remarkably simple Lagrangian description of free massless bosons of any spin, where the kinetic operators take essentially the same form as in the spin-one, Maxwell case.
The construction covers both flat and (A)dS backgrounds and extends to tensors of arbitrary mixed-symmetry type. The resulting actions are related to those emerging from free open string field theory in the tensionless limit. The latter, in their turn, suggest a simple encoding of the corresponding kinetic tensors in terms of higher-spin curvatures.
Arnold Sommerfeld Center