833 research outputs found
SFT non-locality in cosmology: solutions, perturbations and observational evidences
In this note cosmological models coming out of the String Field Theory (SFT)
in application to the Dark Energy are reviewed. A way of constructing solutions
in the case of linear models is outlined, cosmological perturbations and
observational evidences of such models are explored. We explicitly demonstrate
the stability of the system at the linear order in the most typical
configuration.Comment: To be published in Proceedings of Invisible Universe 200
Cosmological Signature of Tachyon Condensation
We consider the dynamics of the open string tachyon condensation in a
framework of the cubic fermionic String Field Theory including a non-minimal
coupling with closed string massless modes, the graviton and the dilaton.
Coupling of the open string tachyon and the dilaton is motivated by the open
String Field Theory in a linear dilaton background and the flat space-time. We
note that the dilaton gravity provides several restrictions on the tachyon
condensation and show explicitly that the influence of the dilaton on the
tachyon condensation is essential and provides a significant effect:
oscillations of the Hubble parameter and the state parameter become of a
cosmological scale. We give an estimation for the period of these oscillations
(0.1-1) Gyr and note a good agreement of this period with the observed
oscillations with a period (0.15-0.65) Gyr in a distribution of quasar spectra.Comment: 19 pages, JHEP3 class; v2: presentation in Section 3 improve
Schwarzschild -singularity is not permissible in ghost free quadratic curvature infinite derivative gravity
In this paper we will study the complete equations of motion for a ghost free
quadratic curvature infinite derivative gravity. We will argue that within the
scale of non-locality, Schwarzschild-type singular metric solution is not {\it
permissible}. Therefore, Schwarzschild-type vacuum solution which is a
prediction in Einstein-Hilbert gravity may {\it not} persist within the region
of non-locality. We will also show that just quadratic curvature gravity,
without infinite derivatives, always allows Schwarzschild-type singular metric
solution.Comment: 10 pages, title changed, discussion added, references updated,
version accepted in PR
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