Special Massive Spin-2 on de Sitter Space

TL;DR

This paper investigates a special massive spin-2 field on de Sitter space, addressing its unique symmetry properties and issues related to coupling and ghost states, proposing a linearized solution to these problems.

Contribution

It introduces a linearized approach to resolve coupling and ghost issues in the special massive spin-2 theory on de Sitter space.

Findings

Enhanced local symmetry identified at specific mass squared.

Problems with coupling to stress-tensor and ghost states addressed.

Proposed linearized solution mitigates known issues.

Abstract

The theory of a massive spin-2 state on the de Sitter space -- with the mass squared equal to one sixth of the curvature -- is special for two reasons: (i) it exhibits an enhanced local symmetry; (ii) it emerges as a part of the model that gives rise to the self-accelerated Universe. The known problems of this theory are: either it cannot be coupled to a non-conformal conserved stress-tensor because of the enhanced symmetry, or it propagates a ghost-like state when the symmetry is constrained by the Lagrange multiplier method. Here we propose a solution to these problems in the linearized approximation.