The Effective Theory of Quintessence: the w<-1 Side Unveiled

Abstract

We study generic single-field dark energy models, by a parametrization of the most general theory of their perturbations around a given background, including higher derivative terms. In appropriate limits this approach reproduces standard quintessence, k-essence and ghost condensation. We find no general pathology associated to an equation of state w_Q < -1 or in crossing the phantom divide w_Q = -1. Stability requires that the w_Q < -1 side of dark energy behaves, on cosmological scales, as a k-essence fluid with a virtually zero speed of sound. This implies that one should set the speed of sound to zero when comparing with data models with w_Q < -1 or crossing the phantom divide. We summarize the theoretical and stability constraints on the quintessential plane (1+w_Q) vs. speed of sound squared.

35 pages, 5 figures, v3: minor modifications, JCAP published version

References in corpus (11)

• The Effective Field Theory of Inflation
• Causality, Analyticity and an IR Obstruction to UV Completion
• Can dark energy evolve to the Phantom?
• Effective Field Theory for Inflation
• Starting the Universe: Stable Violation of the Null Energy Condition and Non-standard Cosmologies
• A Measure of de Sitter Entropy and Eternal Inflation
• Constraining dark energy with cross-correlated CMB and Large Scale Structure data
• Can a galaxy redshift survey measure dark energy clustering?
• The New Ekpyrotic Ghost
• Accelerating Universe and Cosmological Perturbation in the Ghost Condensate
• Constraining the Nature of Dark Energy using the SKA

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