Generalized multi-Galileons, covariantized new terms, and the no-go theorem for nonsingular cosmologies

It has been pointed out that nonsingular cosmological solutions in second-order scalar-tensor theories generically suffer from gradient instabilities. We extend this no-go result to second-order gravitational theories with an arbitrary number of interacting scalar fields. Our proof follows directly...

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Bibliographic Details
Published in:Physical review. D 2017-03, Vol.95 (6), Article 064011
Main Authors: Akama, Shingo, Kobayashi, Tsutomu
Format: Article
Language:English
Subjects:
Field theory
Gravitation theory
Tensors
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Summary:It has been pointed out that nonsingular cosmological solutions in second-order scalar-tensor theories generically suffer from gradient instabilities. We extend this no-go result to second-order gravitational theories with an arbitrary number of interacting scalar fields. Our proof follows directly from the action of generalized multi-Galileons, and thus is different from and complementary to that based on the effective field theory approach. Several new terms for generalized multi-Galileons on a flat background were proposed recently. We find a covariant completion of them and confirm that they do not participate in the no-go argument.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.95.064011