Stable solutions of inflation driven by vector fields

Razieh Emami, Shinji Mukohyama, Ryo Namba, Ying-li Zhang

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Many models of inflation driven by vector fields alone have been known to be plagued by pathological behaviors, namely ghost and/or gradient instabilities. In this work, we seek a new class of vector-driven inflationary models that evade all of the mentioned instabilities. We build our analysis on the Generalized Proca Theory with an extension to three vector fields to realize isotropic expansion. We obtain the conditions required for quasi de-Sitter solutions to be an attractor analogous to the standard slow-roll one and those for their stability at the level of linearized perturbations. Identifying the remedy to the existing unstable models, we provide a simple example and explicitly show its stability. This significantly broadens our knowledge on vector inflationary scenarios, reviving potential phenomenological interests for this class of models.

Original languageEnglish
Article number058
JournalJournal of Cosmology and Astroparticle Physics
Issue number3
Publication statusPublished - 29 Mar 2017
Externally publishedYes


  • cosmological perturbation theory
  • inflation
  • modified gravity


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