Galilean creation of the inflationary universe

It has been pointed out that the null energy condition can be violated stably in some non-canonical scalar-field theories. This allows us to consider the Galilean Genesis scenario in which the universe starts expanding from Minkowski spacetime and hence is free from the initial singularity. We use t...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2015-07, Vol.2015 (7), p.17-17
Main Authors: Kobayashi, Tsutomu, Yamaguchi, Masahide, Yokoyama, Jun'ichi
Format: Article
Language:English
Subjects:
DEGREES OF FREEDOM
FIELD THEORIES
GALACTIC EVOLUTION
INFLATIONARY UNIVERSE
LAGRANGIAN FUNCTION
ORIGIN
PERTURBATION THEORY
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
SCALAR FIELDS
SINGULARITY
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Summary:It has been pointed out that the null energy condition can be violated stably in some non-canonical scalar-field theories. This allows us to consider the Galilean Genesis scenario in which the universe starts expanding from Minkowski spacetime and hence is free from the initial singularity. We use this scenario to study the early-time completion of inflation, pushing forward the recent idea of Pirtskhalava et al. We present a generic form of the Lagrangian governing the background and perturbation dynamics in the Genesis phase, the subsequent inflationary phase, and the graceful exit from inflation, as opposed to employing the effective field theory approach. Our Lagrangian belongs to a more general class of scalar-tensor theories than the Horndeski theory and Gleyzes-Langlois-Piazza-Vernizzi generalization, but still has the same number of the propagating degrees of freedom, and thus can avoid Ostrogradski instabilities. We investigate the generation and evolution of primordial perturbations in this scenario and show that one can indeed construct a stable model of inflation preceded by (generalized) Galilean Genesis.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2015/07/017