Related papers: p-q-superstrings in Anti-de-Sitter space-time
We discuss the linearization of Einstein equations in the presence of a cosmological constant, by expanding the solution for the metric around a flat Minkowski space-time. We demonstrate that one can find consistent solutions to the…
We present spinning Q-balls and boson stars in four dimensional anti-de Sitter spacetime. These are smooth, horizonless solutions for gravity coupled to a massive complex scalar field with a harmonic dependence on time and the azimuthal…
Recent developments in string compactifications demonstrate obstructions to the simplest constructions of low energy cosmologies with positive vacuum energy. The existence of obstacles to creating scale-separated de Sitter solutions…
In this paper we study the effect of the magnetic field in string cosmology for a spatially homogenous and anisotropic Bianchi type -V space-time model. In order to study the effect of magnetic field, the standard form of the energy…
We study the effect of internal space rotation on the gravitational properties of infinite straight and stationary cosmic string. From the approximate solution of Einsten equations for the spinning Q-lump string we obtain long range…
Recent observational data have shown two important results about cosmic inflation: First, the primordial power spectrum is approximately scale invariant. Secondly, the space-time geometry during inflation is quasi-de Sitter. In this paper,…
We study a spatial-temporal structure of quantum fluctuations in the stress-energy tensor of zero-point modes for a scalar field in order to formulate a covariant model. The model describes an invariant vacuum contribution to the…
The quintessence-like potential of vacuum energy can meet the requirement from both quantum gravity and the accelerating expansion of the universe. The anti-de Sitter vacuum in string theory has to be lifted to the meta-stable de Sitter…
The idea that spacetime has to be replaced by Clifford space (C-space) is explored. Quantum field theory (QFT) and string theory are generalized to C-space. It is shown how one can solve the cosmological constant problem and formulate…
We construct non-supersymmetric type I string models which correspond to consistent flat-space solutions of all classical equations of motion. Moreover, the one-loop vacuum energy is naturally fixed by the size of compact extra dimensions…
The presence of tidal charge and a cosmological constant has considerable consequences on the spacetime geometry and its study is much important from the observational point of view. Henceforth, we investigate their effects on particle…
We study cosmic strings in the complex symmetron model, a scalar-tensor theory with a spontaneously broken local $U(1)$ symmetry in low matter density regions. Using numerical simulations, we show that these strings preferentially attach to…
We present results on a new operator for the investigation of string-breaking effects in quenched SU(2)-colour QCD. The ground state of a spatially-separated static-light meson-antimeson pair is a combination of a state with two distinct…
We study the semiclassical evolution of a self-gravitating thick shell in Anti-de Sitter space-time. We treat the matter on the shell as made of quantized bosons and evaluate the back-reaction of the loss of gravitational energy which is…
Using perturbative techniques, we investigate the existence and properties of a new static solution for the Einstein equation with a negative cosmological constant, which we call the deformed black hole. We derive a solution for a static…
Newton's law gets modified in the presence of a cosmological constant by a small repulsive term (antigarvity) that is proportional to the distance. Assuming a value of the cosmological constant consistent with the recent SnIa data ($\Lambda…
We study the classical double copy for static black string solutions in an Anti--de Sitter (AdS) background. By casting the black string metric into Kerr--Schild form over a cylindrical AdS geometry, we construct the corresponding single…
We review some aspects of moduli in string theory. We argue that one should focus on {\it approximate moduli spaces}, and that there is evidence that such spaces exist non-perturbatively. We ask what it would mean for string theory to…
We analyse the Klein-Gordon oscillator in a cosmic string space-time and study the effects stemming from the rotating frame and non-commutativity in momentum space. We show that the latter mimics a constant magnetic field, imparting…
The cosmological constant Lambda affects gravitational lensing phenomena. The contribution of Lambda to the observable angular positions of multiple images and to their amplification and time delay is here computed through a study in the…