950 research outputs found
AdS braneworld with Backreaction
We review the tachyon model derived from the dynamics of a 3-brane moving in
the AdS5 bulk. The bulk geometry is based on the Randall-Sundrum II model
extended to include the radion. The effective tachyon Lagrangian is modified
due to the back-reaction of the brane on the bulk geometry.Comment: 21 pages, 5 figures, typos corrected, a refference added, based on
the talk of NB presented at BW2013 - Beyond the standard models, April 2013,
Vrnjacka Banja, Serbia, to appear in CEJ
Cosmological k-essence condensation
We consider a model of dark energy/matter unification based on a k-essence
type of theory similar to tachyon condensate models. Using an extension of the
general relativistic spherical model which incorporates the effects of both
pressure and the acoustic horizon we show that an initially perturbative
k-essence fluid evolves into a mixed system containing cold dark matter like
gravitational condensate in significant quantities.Comment: 8 pages, 2 figures, presented by NB at the conference Beyond 2010,
Cape Town, 1-6 February 201
Cosmological tachyon condensation
We consider the prospects for dark matter/energy unification in k-essence
type theories. General mappings are established between the k-essence scalar
field, the hydrodynamic and braneworld descriptions. We develop an extension of
the general relativistic dust model that incorporates the effects of both
pressure and the associated acoustic horizon. Applying this to a tachyon model,
we show that this inhomogeneous "variable Chaplygin gas" does evolve into a
mixed system containing cold dark matter like gravitational condensate in
significant quantities. Our methods can be applied to any dark energy model as
well as to mixtures of dark energy and traditional dark matter.Comment: 22 pages, 3 figures, title changed, typos corrected, accepted in
Phys. Rev.
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