Generalized Proca and its Constraint Algebra

Understand

We reconsider the construction of general derivative self-interactions for a massive Proca field.

• The constructed Lagrangian is such that the vector field propagates at most three degrees of freedom, thus avoiding the ghostly nature of a fourth polarisation.
• The construction makes use of the well-known condition for constrained systems of having a degenerate Hessian.
• We briefly discuss the casuistry according to the nature of the existing constraints algebra.