Notes on a Cure for Higher-Spin Acausality

TL;DR

This paper introduces a Lagrangian for a massive charged spin-2 field and scalar in electromagnetic backgrounds, derived from string theory, which maintains causality and correct degrees of freedom across dimensions.

Contribution

It provides a consistent Lagrangian for higher-spin fields that addresses acausality issues by adding finitely many degrees of freedom, extending previous models.

Findings

Propagates correct degrees of freedom within the light cone

Derived from string field theory via dimensional reduction

Addresses higher-spin acausality problems

Abstract

We present a Lagrangian describing a massive charged spin-2 field and a scalar in a constant electromagnetic background, and we provide a consistent description of the system. The Lagrangian, derived from string field theory through a suitable dimensional reduction, propagates the correct number of degrees of freedom within the light cone in any space-time dimension less than 26. We briefly discuss the higher-spin generalization of this construction, that cures the pathologies of a massive charged particle of arbitrary integer spin by introducing only finitely many new massive degrees of freedom.