Helicity and spin conservation in Maxwell theory and Linearized Gravity

Understand

A duality symmetric formulation of linearized gravity has been introduced by Barnett and used to show the conservation of helicity.

• However, the relation between helicity and spin as well as the separate conservation of the spin and orbital parts of angular momentum, which is known to hold in Maxwell theory, was not considered.
• These conservation laws are known to follow from the conservation of the so-called helicity array, an analog of the zilch tensor, which includes helicity, spin, and spin-flux or infra-zilch.
• In the present paper we prove the conservation of spin and orbital angular momentum for linearized gravity on Minkowski space, and construct the analog of the helicity array for linearized gravity.