Related papers: Cosmological Constant Behavior in DBI Theory
In this paper we use $\alpha'^2$-corrections to the $D_{3}$-brane action to obtain a non-zero and positive cosmological constant in the induced cosmology living on the dark bubble. Its measured value, together with the value of the fine…
We study cosmological solutions to the low-energy effective action of heterotic string theory including possible leading order $\alpha'$ corrections and a potential for the dilaton. We consider the possibility that including such stringy…
We consider scalar tensor theories in D-dimensional spacetime, D \ge 4. They consist of metric and a non minimally coupled scalar field, with its non minimal coupling characterised by a function. The probes couple minimally to the metric…
The continuous and discrete symmetries of a dimensionally reduced type IIB superstring action are employed to generate four-dimensional cosmological solutions with non-trivial Neveu-Schwarz/Neveu-Schwarz and Ramond-Ramond form-fields from…
The quantum field theory prediction of the cosmological constant is 120 orders of magnitude higher than the observed value. This is known as the cosmological constant problem. Here, we deal with the cosmological constant as a scalar field…
We construct new classes of exact cosmological solutions to five dimensional Einstein-Maxwell-dilaton theory with two coupling constants for the dilaton-Maxwell term and dilaton-cosmological constant term. All the solutions are…
We show the kinematic equivalence between cosmological models driven by Dirac-Born-Infeld fields $\phi$ with constant proper velocity of the brane and exponential potential $V=V_0e^{-B\phi}$ and interactive cosmological systems with…
We study the effect of higher-curvature terms in the string low-energy effective actions on the cosmological solutions of the theory, up to corrections quartic in the curvatures, for the bosonic and heterotic strings as well as the type II…
We study the cosmological implications of including angular motion in the DBI brane inflation scenario. The non-canonical kinetic terms of the Dirac-Born-Infeld action give an interesting alternative to slow roll inflation, and cycling…
We consider a generalized Brans-Dicke model in which the scalar field has a self-interacting potential function. The scalar field is also allowed to couple non-minimally with the matter part. We assume that it has a chameleon behavior in…
The ten-dimensional type IIA string effective action with cosmological constant term is dimensionally reduced on a d-dimensional torus to derive lower dimensional effective action. The symmetries of the reduced effective action are…
In this paper we seek for relevant information on the asymptotic cosmological dynamics of the Brans--Dicke theory of gravity for several self-interaction potentials. By means of the simplest tools of the dynamical systems theory, it is…
We study dynamics of rolling tachyon and Abelian gauge field on unstable D-branes, of which effective action is given by Born-Infeld type nonlocal action. Possible cosmological evolutions are also discussed. In the Einstein frame of string…
We examine the plausibility of crossing the cosmological constant ($\L$) barrier in a two-field quintessence model of dark energy, involving a kinetic interaction between the individual fields. Such a kinetic interaction may have its origin…
Time-dependent solutions of bosonic string theory resemble renormalisation group trajectories in the space of 2d field theories: they often interpolate between repulsive and attractive static solutions. It is shown that the attractive…
One of the greatest problems of standard cosmology is the Big Bang singularity. Previously it has been shown that non-local ghostfree higher-derivative modifications of Einstein gravity in the ultra-violet regime can admit non-singular…
It has been proposed that the geometry of an extra dimension could automatically adjust itself to compensate for an arbitrary energy density on the 3-D brane which we are presumed to inhabit, such that a static solution to Einstein's…
This diploma thesis analyses static, spherically symmetric perfect fluid solutions to Einstein's field equations with cosmological constant. Constant density solutions are derived for different values of the cosmological constant. Eleven…
We study the cosmological dynamics of D-BIonic and DBI scalar field, which is coupled to matter fluid. For the exponential potential and the exponential couplings, we find a new analytic scaling solution yielding the accelerated expansion…
We propose, based on the viewpoint that our three-dimensional space is a stack of BPS D3-branes located at the conifold singularity of the Calabi-Yau three-fold, a new mechanism to address the cosmological constant problem in the framework…