Frame-like Actions for Massless Mixed-Symmetry Fields in Minkowski space

TL;DR

The paper constructs a frame-like action for arbitrary massless mixed-symmetry bosonic fields in Minkowski space, yielding a simple two-term Lagrangian for any field spin with tensor-valued differential-form fields and gauge parameters. It builds on the unfolded formulation of the equations for mixed-symmetry fields to achieve manifest gauge invariance in a first-order, frame-like setting. By avoiding the heavy double-trace constraints of the constrained approach, the action provides a compact, local description that integrates naturally with unfolded dynamics and has potential for consistent interactions and nonlinear extensions. The work clarifies the relationship between Labastida's constrained framework and the unfolded frame-like picture, highlighting practical advantages for constructing covariant higher-spin theories.

Abstract

A frame-like action for arbitrary mixed-symmetry bosonic massless fields in Minkowski space is constructed. The action is given in a simple form and consists of two terms for a field of any spin. The fields and gauge parameters are certain tensor-valued differential forms. The formulation is based on the unfolded form of equations for mixed-symmetry fields.