In this paper we construct a stringy embedding of the dark bubble model an expanding 4D cosmology with help branes rotating in extra dimensions. The Universe rides which has nucleated unstable higher dimensional background. Our construction is therefore string theoretical realization Vilenkin's quantum cosmology. While cosmological constant vanishes at lowest order, loop corrections predicted b...

We review (and extend) the analysis of general theories all interactions (gravity included) where mass scales are due to dimensional transmutation. Quantum consistency requires presence terms in action with four derivatives metric. It is shown, nevertheless, how unitary achieved and classical Ostrogradsky instabilities can be avoided. The four-derivative also allow us have a UV complete framewo...

One of the aims of braneworld cosmology is to identify a ‘smoking gun’ for the existence of large extra dimensions by means of observations of the early universe. Braneworld cosmology has succeeded in reproducing the conventional cosmology at late times in a higher-dimensional context, but finding a unique observational signature has proved elusive. Here we demonstrate that the recently propose...

We investigate cosmological solutions of eleven dimensional supergravity compactified on a squashed seven manifold. The effective action for the four dimensional theory contains scalar fields describing the size and squashing of the compactifying space. The potential for these fields consists of a sum of exponential terms. We derive a criterion for an exponential potential to give rise to infla...

We consider a five-dimensional Einstein-Chern-Simons action which is composed of gravitational sector and matter, where the given by Chern-Simons gravity instead Einstein-Hilbert action, matter perfect fluid. The lagrangian obtained gauging some Lie-algebras, in turn, were S-expansion procedure Anti-de Sitter de algebras. On cosmological plane, we discuss field equations resulting from framewor...

We investigate the evolution of the homogeneous and isotropic universe within the framework of the effective string gravity with string-loop modifications of dilaton couplings. In the case of barotropic perfect fluid as a nongravitational source the set of cosmological equations is presented in the form of the third-order autonomous dynamical system. The cases are considered when this system is...

In the context of higher-dimensional cosmologies we study the conditions under which adiabatic expansion of the visible external space is possible, when a time-dependent internal space is present. The analysis is based on a reinterpretation of the four-dimensional stress-energy tensor in the presence of the extra dimensions. This modifies the usual adiabatic energy conservation laws for the vis...