748 research outputs found
Cyclic Cosmology from the Little Rip
We revisit a cyclic cosmology scenario proposed in 2007 to examine whether
its hypotheses can be sustained if the underlying big rip evolution, which was
assumed there, is replaced by the recently proposed little rip. We show that
the separation into causal patches at turnaround is generally valid for a
little rip, and therefore conclude that the little rip is equally as suitable a
basis for cyclicity as is the big rip.Comment: 5 pages. arXiv admin note: substantial text overlap with
arXiv:hep-th/061021
Possible Couplings of Dark Matter
Dark matter interacts gravitationally, but it presumably interacts weakly through other channels, especially with respect to regular luminous matter. We look at different ways in which dark matter may couple to other fields. We briefly review some example approaches in the literature for modeling the coupling between dark energy and dark matter and examine the possibility of an arguably better-motivated approach via non-minimal coupling between a scalar field and the Ricci scalar, which is necessary for renormalization of the scalar field in curved space-time. We also show an example of a theory beyond the Standard Model in which dark matter is uniquely connected to the inflaton, and we use observational astrophysical constraints to specify an upper bound on the dark matter mass. In turn, this mass constraint implies a limit on the unification scale of the theory, a decoupling scale of the theory, and the number of
e
-folds of inflation allowed
Alien Registration- Gondek, Ludwick (Wilton, Franklin County)
https://digitalmaine.com/alien_docs/19486/thumbnail.jp
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