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Bi-galileon theory I: motivation and formulation

Padilla, Antonio; Saffin, Paul M.; Zhou, Shuang-Yong


Shuang-Yong Zhou


We introduce bi-galileon theory, the generalisation of the single galileon model introduced by Nicolis et al. The theory contains two coupled scalar fields and is described by a Lagrangian that is invariant under Galilean shifts in those fields. This paper is the first of two, and focuses on the motivation and formulation of the theory. We show that the boundary effective theory of the cascading cosmology model corresponds to a bi-galileon theory in the decoupling limit, and argue that this is to be expected for co-dimension 2 braneworld models exhibiting infra-red modification of gravity. We then generalise this, by constructing the most general bi-galileon Lagrangian. By coupling one of the galileons to the energy-momentum tensor, we pitch this as a modified gravity theory in which the modifications to General Relativity are encoded in the dynamics of the two galileons. We initiate a study of phenomenology by looking at maximally symmetric vacua and their stability, developing elegant geometric techniques that trivially explain why some of the vacua have to be unstable in certain cases (eg DGP). A detailed study of phenomenology appears in our companion paper.


Padilla, A., Saffin, P. M., & Zhou, S. (2010). Bi-galileon theory I: motivation and formulation. Journal of High Energy Physics, 2010(12),

Journal Article Type Article
Acceptance Date Dec 1, 2010
Publication Date Dec 6, 2010
Deposit Date Apr 21, 2017
Publicly Available Date Apr 21, 2017
Journal Journal of High Energy Physics
Electronic ISSN 1029-8479
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 2010
Issue 12
Public URL
Publisher URL
Copyright Statement Copyright information regarding this work can be found at the following address:


1007.5424.pdf (288 Kb)

Copyright Statement
Copyright information regarding this work can be found at the following address:

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