Lagrangian for massless gravitational field in de Sitter space

Local or gauge symmetries are fundamental in elementary-particle physics to describes electroweak and strong interactions in the standard model. The gauge symmetry underlies the dynamics and is employed to describe the interaction between fields. For obtaining a gauge-invariant Lagrangian, the gauge-covariant derivative is defined such that any gauge fields are associated with the generators of the local symmetry group. In this paper, we obtain the gauge-covariant derivative and the gauge-invariant Lagrangian density in de Sitter ambient space formalism.