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

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dc.creatorCreminelli, Paolo
dc.creatorD'Amico, Guido
dc.creatorNoreña, Jorge
dc.creatorVernizzi, Filippo
dc.date2008-11-05
dc.date2009-02-16
dc.date.accessioned2026-07-07T12:41:50Z
dc.date.available2026-07-07T12:41:50Z
dc.descriptionWe 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.
dc.description35 pages, 5 figures, v3: minor modifications, JCAP published version
dc.identifierhttps://arxiv.org/abs/0811.0827
dc.identifierhttp://arxiv.org/abs/0811.0827
dc.identifierJCAP 0902:018,2009
dc.identifierdoi:10.1088/1475-7516/2009/02/018
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/219875
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Theory
dc.titleThe Effective Theory of Quintessence: the w<-1 Side Unveiled
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