Derivative self-interactions for a massive vector field

TL;DR

This paper systematically constructs and classifies derivative self-interactions for a massive vector (Proca) field, ensuring only the three physical polarizations propagate, and extends the results to curved spacetime with gravity.

Contribution

It provides a comprehensive method to derive healthy derivative self-interactions for a Proca field, including a determinantal form and generalization to curved backgrounds.

Findings

Finite family of allowed derivative interactions identified.

Higher order terms trivialized in 4D via Cayley-Hamilton theorem.

Interactions can be expressed in a determinantal form similar to Born-Infeld.

Abstract

In this work we revisit the construction of theories for a massive vector field with derivative self-interactions such that only the 3 desired polarizations corresponding to a Proca field propagate. We start from the decoupling limit by constructing healthy interactions containing second derivatives of the Stueckelberg field with itself and also with the transverse modes. The resulting interactions can then be straightforwardly generalized beyond the decoupling limit. We then proceed to a systematic construction of the interactions by using the Levi-Civita tensors. Both approaches lead to a finite family of allowed derivative self-interactions for the Proca field. This construction allows us to show that some higher order terms recently introduced as new interactions trivialize in 4 dimensions by virtue of the Cayley-Hamilton theorem. Moreover, we discuss how the resulting derivative interactions can be written in a compact determinantal form, which can also be regarded as a generalization of the Born-Infeld lagrangian for electromagnetism. Finally, we generalize our results for a curved background and give the necessary non-minimal couplings guaranteeing that no additional polarizations propagate even in the presence of gravity.