On the stability and causality of scalar-vector theories

Abstract

Various extensions of standard inflationary models have been proposed recently by adding vector fields. Because they are generally motivated by large-scale anomalies, and the possibility of statistical anisotropy of primordial fluctuations, such models require to introduce non-standard couplings between vector fields on the one hand, and either gravity or scalar fields on the other hand. In this article, we study models involving a vector field coupled to a scalar field. We derive restrictive necessary conditions for these models to be both stable (Hamiltonian bounded by below) and causal (hyperbolic equations of motion).

20 pages, references added, v2 matches published version in JCAP

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Cited by in corpus (9)

• Generalized SU(2) Proca Theory
• Anisotropic cosmological solutions in massive vector theories
• Stealth magnetic field in de Sitter spacetime
• Suppression of matter couplings with a vector field in generalized Proca theories
• Anisotropic inflation with coupled $\mathbf{p}$-forms
• Can we explain cosmic birefringence without a new light field beyond Standard Model?
• Anisotropic Scalar Field Dark Energy with a Disformally Coupled Yang-Mills Field
• Absence of solid angle deficit singularities in beyond-generalized Proca theories
• de Sitter symmetries and inflationary correlators in parity violating scalar-vector models