Restricted Galileons

Lasha Berezhiani, Giga Chkareuli, Gregory Gabadadze

    Research output: Contribution to journalArticle

    Abstract

    We study Galileon theories that emerge in ghost-free massive gravity. In particular, we focus on a subclass of these theories where the Galileons can be completely decoupled from the tensor Lagrangian. These Galileons differ from generic ones - they have interrelated coefficients of the cubic and quartic terms, and most importantly, a nonstandard coupling to external stress-tensors, governed by the same coefficient. We show that this theory has no static stable spherically symmetric solutions that would interpolate from the Vainshtein region to flat space; these two regions cannot be smoothly matched for the sign of the coefficient for which fluctuations are stable. Instead, for this sign choice, a solution in the Vainshtein domain is matched onto a cosmological background. Small fluctuations above this solution are stable, and sub-luminal. We discuss observational constraints on this theory, within the quantum effective Lagrangian approach, and argue that having a graviton mass of the order of the present-day Hubble parameter, is consistent with the data. Last but not least, we also present a general class of cosmological solutions in this theory, some of which exhibit the demixing phenomenon, previously found for the self-accelerated solution.

    Original languageEnglish (US)
    Article number124020
    JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
    Volume88
    Issue number12
    DOIs
    StatePublished - Dec 9 2013

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics
    • Physics and Astronomy (miscellaneous)

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