Chiral approach to massive higher spins

TL;DR

This paper introduces a new chiral framework for describing massive higher-spin particles in four dimensions, enabling consistent interactions with gauge fields and gravity, and providing explicit scattering amplitude calculations.

Contribution

It presents the first consistent interacting field theories for massive higher-spin particles using a chiral approach with simple Lagrangians.

Findings

Derived tree-level scattering amplitudes for higher-spin matter with gauge bosons and gravitons.

Reproduced known on-shell recursion results for arbitrary multiplicities.

Provided the only known examples of consistent interacting massive higher-spin theories.

Abstract

We propose a new, chiral description for massive higher-spin particles in four spacetime dimensions, which facilitates the introduction of consistent interactions. As proof of concept, we formulate three theories, in which higher-spin matter is coupled to electrodynamics, non-Abelian gauge theory or gravity. The theories are chiral and have simple Lagrangians, resulting in Feynman rules analogous to those of massive scalars. Starting from these Feynman rules, we derive tree-level scattering amplitudes with two higher-spin matter particles and any number of positive-helicity photons, gluons or gravitons. The amplitudes reproduce the arbitrary-multiplicity results that were obtained via on-shell recursion in a parity-conserving setting, and which chiral and non-chiral theories thus have in common. The presented theories are currently the only examples of consistent interacting field theories with massive higher-spin fields.