Results 21 to 30 of about 678,025 (58)

Dilatonic, Current-Carrying Cosmic String [PDF]

, 1999
We study the implications of a scalar-tensorial gravity for the metric of an isolated self-gravitating superconducting cosmic string. These modifications are induced by an arbitrary coupling of a massless scalar field to the usual tensorial field in the gravitational Lagrangian.
arxiv   +1 more source

Instant preheating mechanism and UHECR [PDF]

Phys.Rev. D70 (2004) 023003, 2004
Top-down models assume that the still unexplained Ultra High Energy Cosmic Rays (UHECR's) are the decay products of superheavy particles. Such particles may have been produced by one of the post-inflationary reheating mechanisms and may account for a fraction of the cold dark matter.
arxiv   +1 more source

Perturbed Einstein field equations using Maple [PDF]

arXiv, 2003
We obtain the perturbed components of affine connection and Ricci tensor using algebraic computation. Naturally, the perturbed Einstein field equations for the vacuum can be written. The method can be used to obtain perturbed equations of the superior order.
arxiv  

Ultralocality on the lattice [PDF]

arXiv, 2002
It is shown that the nonlocal Dirac operator yielded by a lattice model that preserves chiral symmetry and uniqueness of fields, approaches to an ultralocal and invariant under translations operator when the size of the lattice tends to zero.
arxiv  

Constrained Variational Calculus for Higher Order Classical Field Theories [PDF]

, 2010
We develop an intrinsic geometrical setting for higher order constrained field theories. As a main tool we use an appropriate generalization of the classical Skinner-Rusk formalism. Some examples of application are studied, in particular, applications to the geometrical description of optimal control theory for partial differential equations.
arxiv   +1 more source

Updated Limits on Visibly and Invisibly Decaying Higgs Bosons from LEP [PDF]

arXiv, 1994
Talk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994 ...
arxiv  

Exact solutions for the spatial de Vaucouleurs and Sersic laws and related quantities [PDF]

, 2001
Using the Mathematica package, we find exact analytical expressions for the so-called de-projected De Vaucouleurs and Sersic laws as well as for related spatial (3D) quantities, such the mass, gravitational potential, the total energy and the central velocity dispersion, generally involved in astronomical calculations expressed in terms of the Meijer G
arxiv   +1 more source

Growing of the Inhomogeneities with Particle Production [PDF]

arXiv, 1999
Perturbations in Prigogine's cosmological model with particle creation are investigated in the framework of Newtonian Theory. The necessary conditions for the density contrast to reach the non-linear regime wich is necessary to garantee structure formation at large scale are obtained.
arxiv  

Evolution of the Density Contrast with Particle Production in a Gauge-Invariant Formalism [PDF]

arXiv, 2001
In this work we derive the evolution equation for the density contrast considering open system cosmology, where the influence of adiabatic particle production process on the dynamic of a homogeneous and isotropic is investigated within a manifestly covariant formulation.
arxiv  

Chen-Wu type model and the total energy of the universe [PDF]

arXiv, 2004
The inclusion of a $\Lambda $ term, today, in the relativistic field equations is consequence of the evolution of an observational cosmology. In this work we argue the "ansatz" $\Lambda = \beta H^2 +\frac{\alpha}{R^2}$ is applicable to the total energy density of the universe, discuss some cosmological consequences and compare the growing mode of the ...
arxiv