Polarization tensor in de Sitter gauge gravity

TL;DR

This paper develops a gauge theory framework for de Sitter gravity, constructing spin-2 tensor fields with mixed symmetry, and explores their polarization properties relevant for gravitational wave analysis.

Contribution

It introduces a novel representation of spin-2 fields in de Sitter space using mixed symmetry tensors and connects their transformation properties to conformal and de Sitter groups.

Findings

Constructed gauge-invariant field equations for de Sitter gauge vector fields.

Derived a mixed symmetry rank-3 tensor field for spin-2 representation.

Linked polarization tensors to gravitational wave considerations in de Sitter space.

Abstract

The gauge theory of the de Sitter group, SO$(1,4)$, in the ambient space formalism has been considered in this article. This method is essential to constructing the de Sitter super-conformal gravity and Quantum gravity. $10$ gauge vector fields are needed, corresponding to $10$ generators of the de Sitter group. Using the gauge-invariant Lagrangian, the field equation of these vector fields has been obtained. The gauge vector field solutions are recalled. Then, the spin-$2$ gauge potentials are constructed from the gauge vector field. There are two possibilities for presenting this tensor field: rank-$2$ symmetric and mixed symmetry rank-$3$ tensor fields. To preserve the conformal transformation, a spin-$2$ field must be represented by a mixed symmetry rank-$3$ tensor field, $\mathcal {K}_{\alpha\beta\gamma}$. This tensor field has been rewritten using a generalized polarization tensor field and a de Sitter plane wave. This generalized polarization tensor field has been calculated as a combination of vector polarization, $\mathcal {E}_{\alpha}$, and tensor polarization of rank-$2$, $\mathcal {E}_{\alpha\beta}$, which can be used in the gravitational wave consideration. For the construction of this polarization tensor, the arbitrary constant vector fields appear. We fix it so that, in the limit, $H=0$, one obtains the polarization tensor in Minkowski space-time. It has been shown that under some simple conditions, the spin-$2$ mixed symmetry rank-$3$ tensor field can be simultaneously transformed by the unitary irreducible representation of de Sitter and conformal groups, SO$(2,4)$.