Related papers: New solutions with accelerated expansion in string…
Analytic solutions to low-energy string theory, which describe arbitrary numbers of extreme `black holes (strings)' in linear dilaton vacua, are found.
We study de Sitter configurations in ten-dimensional string models where supersymmetry is either absent or broken at the string scale. To this end, we derive expressions for the cosmological constant in general warped flux compactifications…
Biadjoint scalar field theories are increasingly important in the study of scattering amplitudes in various string and field theories. Recently, some first exact nonperturbative solutions of biadjoint scalar theory were presented, with a…
We develop velocity-dependent models describing the evolution of string networks that involve several types of interacting strings, each with a different tension. These incorporate the formation of Y-type junctions with links stretching…
We explore the possibility that our universe's current accelerated expansion is explained by a quintessence model with an exponential scalar potential, $V =V_0\, e^{-\lambda\, \phi}$, keeping an eye towards $\lambda \geq \sqrt{2}$ and an…
We attempt to understand the fate of spacelike gravitational singularities in string theory via the quantum stress tensor for string matter in a fixed background. We first approximate the singularity with a homogeneous anisotropic…
We explore the possibility of solving the dark energy and the coincidence problems by postulating the massless sector of closed strings. This sector constitutes the gravitational multiplet of string theory and, when applied to…
It has recently been argued that string theory does not admit de Sitter vacua. This would imply that the current accelerated expansion of the universe is not driven by a cosmological constant (or vacuum energy) but by other means such as a…
We study classical solutions of a low energy effective theory of a string theory with tachyons. With a certain ansatz, we obtain all possible solutions which are weakly coupled and weakly curved. We find, in addition to the interpolating…
We demonstrate how exponential potentials that could arise in the early Universe as a result of Kaluza-Klein type compactifications of string theory, can lead to cosmological solutions which correspond to the currently observed accelerating…
In this paper, a new class of string and holographic dark energy (HDE) cosmological model in the context of the $f(R)$ theory of gravity using the Kasner metric is considered. The exact solution of the field equations is obtained using the…
We review applications of string theory to cosmology, from primordial times to the present-day accelerated expansion. Starting with a brief overview of cosmology and string compactifications, we discuss in detail moduli stabilisation,…
We construct a novel solution in the low energy limit of heterotic string theory describing accelerating charged and rotating black holes with NUT parameter. Some aspects of the new spacetime are discussed, such as locations of horizons,…
In the modified measure formulation the string tension appear as an additional dynamical degree of freedom and these tensions are not universal, but rather each string generates its own tension, which can have a different value for each…
Observational evidence suggests that our universe is presently dominated by a dark energy component and undergoing accelerated expansion. We recently introduced a model, motivated by string theory for short-distance physics, for explaining…
In General Relativity, cosmic strings are well known to produce a static, locally flat spacetime with a wedge removed. If the tension exceeds a critical value, the deficit angle becomes larger than $ 2\pi $, leading to a compact exterior…
We examine the focusing of kinetic energy and the amplification of various quantities during the snapping motion of the free end of a flexible structure. This brief but violent event appears to be a regularized finite-time singularity, with…
We study the possibility of extended inflation in the effective theory of gravity from strings compactified to four dimensions and find that it strongly depends on the mechanism of supersymmetry breaking. We consider a general class of…
Recent observations indicate that the universe's expansion has been accelerating of late. But recent theoretical work has highlighted the difficulty of squaring acceleration with the underlying assumptions of string theory, disfavoring most…
Cosmological solutions are obtained by continuation of black D-brane solutions into the region between the horizons. It is investigated whether one can find exponential expansion when probing the cosmology with D-branes. A unique…