de Sitter tachyons and related topics

Understand

We present a complete study of a family of tachyonic scalar fields living on the de Sitter universe.

• We show that for an infinite set of discrete values of the negative squared mass the fields exhibit a gauge symmetry and there exists for them a fully acceptable local and covariant quantization similar to the Feynman-Gupta-Bleuler quantization of free QED.
• For general negative squares masses we also construct positive quantization where the de Sitter symmetry is spontaneously broken.
• We discuss the sense in which the two quantizations may be considered physically inequivalent even when there is a Lorentz invariant subspace in the second one.