We analyze the constraints obtained from new atomic clock data on thepossible time variation of the fine structure `constant' and theelectron-proton mass ratio and show how they are strengthened when the seasonalvariation of Sun's gravitational field at the Earth's surface

We study a three dimensional non-commutative space emerging in the context ofthree dimensional Euclidean quantum gravity. Our starting point is theassumption that the isometry group is deformed to the Drinfeld double D(SU(2)).We generalize to the deformed case the construction of

Wolfgang Kummer was a pioneer of two-dimensional gravity and a strongadvocate of the first order formulation in terms of Cartan variables. In thepresent work we apply Wolfgang Kummer's philosophy, the `Vienna Schoolapproach', to a specific three-dimensional model of gravity, cosmologicaltopologically

The dissipative dynamics anticipated in the proof of 't Hooft's existencetheorem -- "For any quantum system there exists at least one deterministicmodel that reproduces all its dynamics after prequantization" -- is constructedhere explicitly. We propose a generalization of Liouville's classical

We investigate the models of dark energy with purely kinetic multiplek-essence sources that allows for the crossing of the phantom divide line,without violating the conditions of stability. It is known that with more thanone kinetic k-field one can possibly construct

We consider the conditions for integrating out heavy chiral fields and moduliin N=1 supergravity, subject to two explicit requirements. First, the VEV ofthe heavy fields should be unaffected by low energy phenomena. Second, the lowenergy effective action should be described

We study the dynamics of domain walls in Einstein-Born-Infeld-dilaton theory.Dilaton is non-trivially coupled with the Born-Infeld electromagnetic field. Wefind three different types of solutions consistent with the dynamic domainwalls. For every case, the solutions have singularity. Further more, in thesebackgrounds,

We argue that a version of the four dimensional Brans-Dicke theory can beembedded in the standard flat spacetime electroweak theory. The embeddinginvolves a change of variables that separates the isospin from the hyperchargein the electroweak theory.

Quantum fluctuations in the post inflationary Affleck-Dine baryogenesis modelare studied. The squeezed states formalism is used to give evolution equationsfor the particle and anti-particle modes in the early universe. The role ofexpansion and parametric amplification of the quantum fluctuations on

Using the cut-and-paste procedure, we construct static and dynamic planesymmetric wormholes by surgically grafting together two spacetimes of planesymmetric vacuum solutions with a negative cosmological constant. These planesymmetric wormholes may be viewed as domain walls connecting differentuniverses, having planar topology,

An analytic model a la Middleton of the impulsive noise component in the dataof interferometric gravitational wave detectors is proposed, based on an atomicrepresentation of glitches. A fully analytic characterization of the coherentnetwork data analysis algorithm proposed by Rakhmanov and

A generic `chirp' of the form h(t) = A(t) cos(phi(t)) can be closelyapproximated by a connected set of multiscale chirplets withquadratically-evolving phase. The problem of finding the best approximation toa given signal using chirplets can be reduced to that of

In this work, we consider different forms of relativistic perfect fluidLagrangian densities, that yield the same gravitational field equations inGeneral Relativity. A particularly intriguing example is the case withcouplings of the form $[1+f_2(R)]{\cal L}_m$, where $R$ is the scalarcurvature, which

We investigate the Gauss-Bonnet black hole in five dimensional anti-de Sitterspacetimes (GBAdS). We analyze all thermodynamic quantities of the GBAdS, whichis characterized by the Gauss-Bonnet coupling $c$ and mass $M$, comparing withthose of the Born-Infeld-AdS (BIAdS), Reissner-Norstr\"om-AdS black holes(RNAdS), Schwarzschild-AdS

We argue that the cosmological constant is exponentially suppressed in acandidate ground state of loop quantum gravity as a nonperturbative effect of aholographic Fermi-liquid theory living on a two-dimensional spacetime. Ashtekarconnection components, corresponding to degenerate gravitational configurationsbreaking large gauge invariance