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A natural consequence of string theory is a non-commutative structure of space-time on microscopic scales. The existence of a minimal length, and a modification of the effective field theory are two consequences of this space-time…

High Energy Physics - Theory · Physics 2008-11-26 Robert Brandenberger

We study the formation of cosmic strings by confining a stochastic magnetic field into flux tubes in a numerical simulation. We use overdamped evolution in a potential that is minimized when the flux through each face in the simulation…

High Energy Physics - Theory · Physics 2008-11-26 Jose J. Blanco-Pillado , Ken D. Olum , Alexander Vilenkin

In this Reply, using G.de.A.Marques' comment, we correct calculations and results presented in [Phys.Lett.B 632(2006) 151-154] about corrections to the fine structure constant in the spacetime of a cosmic string from the generalized…

High Energy Physics - Theory · Physics 2008-11-26 Forough Nasseri

The model of cosmic string formed from two gravitating and interacting scalar fields is considered. It is shown that the regular solutions exist at special choice of the model's parameters only.

General Relativity and Quantum Cosmology · Physics 2010-05-27 V. Dzhunushaliev , V. Folomeev , K. Myrzakulov , R. Myrzakulov

Recent cosmological observations suggest the existence of a positive cosmological constant $\Lambda$ with the magnitude $\Lambda(G\hbar/c^3) \approx 10^{-123}$. This review discusses several aspects of the cosmological constant both from…

High Energy Physics - Theory · Physics 2008-11-26 T. Padmanabhan

It is known that Vilenkin's phenomenological equation of state for static straight cosmic strings is inconsistent with Brans-Dicke theory. We will prove that, in the presence of a cosmological constant, this equation of state is consistent…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ozgur Delice

The cosmological constant is an unexplained until now phenomena of nature that requires an explanation through string effects. The apparent discrepancy between theory and experiment is enourmous and has already been explained several times…

General Physics · Physics 2007-05-23 Gordon Chalmers

Making use of the wealth of new observational data coming from the sky it is possible to constrain particle physics theories beyond the Standard Model. One way to do this is illustrated in this article: a subset of theories admits cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-21 Robert H. Brandenberger

We argue that cosmic strings with high winding numbers generally form in first-order gauge symmetry breaking phase transitions, and we demonstrate this using computer simulations. These strings are heavier than single-winding strings and…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Donaire , A. Rajantie

Theories of the cosmological constant fall into two classes, those in which the vacuum energy is fixed by the fundamental theory and those in which it is adjustable in some way. For each class we discuss key challenges. The string theory…

High Energy Physics - Theory · Physics 2007-05-23 Joseph Polchinski

We present results for the cosmic non-linear density-fluctuation power spectrum based on the analytical formalism developed in [1] which allows us to study cosmic structure formation based on Newtonian particle dynamics in phase-space. This…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Tristan Daus , Elena Kozlikin

The canonical Monte-Carlo algorithm for simulating the production of string-like topological defects at a phase transition is extended by introducing a distribution of domain sizes. A strong correlation is found between the fraction in the…

High Energy Physics - Phenomenology · Physics 2009-10-28 Andrew Yates , T. W. B. Kibble

${\rm B - L}$ cosmic strings form in a wide class of theories beyond the Standard Model which contain a ${\rm U}(1)_{{\rm B - L}}$ gauge symmetry. They can form at the end of hybrid inflation and explain, together with inflation, the Cosmic…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. Jeannerot

We study structure formation in the late Universe within the Vlasov kinetic self-consistent field approach. Our work is principally focused on the use of the modified gravitational potential with a repulsive term of the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-28 V. G. Gurzadyan , N. N. Fimin , V. M. Chechetkin

Cosmic strings are linear concentrations of energy that may be formed at phase transitions in the very early universe. At one time they were thought to provide a possible origin for the density inhomogeneities from which galaxies eventually…

High Energy Physics - Theory · Physics 2009-11-11 A. -C. Davis , T. W. B. Kibble

The classical electromagnetic modes outside a long, straight, superconducting cosmic string are calculated, assuming the string to be surrounded by a superconducting cylindric surface of radius R. Thereafter, by use of a Bogoliubov-type…

General Relativity and Quantum Cosmology · Physics 2009-01-14 I. Brevik , A. G. Frøseth

A synthetic report of the advances in the study of classical and quantum string dynamics in curved backgrounds is provided, namely: the new feature of multistring solutions; the effect of a cosmological constant and of spacial curvature on…

High Energy Physics - Theory · Physics 2011-07-19 Norma G. Sanchez

In the paper Phys. Lett. B614 (2005), 140-142, F. Nasseri shows that the values of the fine structure constant reduces due to the presence of a cosmic string. In this comment I want to point out that this conclusion is not completely…

High Energy Physics - Theory · Physics 2008-11-26 E. R. Bezerra de Mello

We give a simple derivation of a new formal expression for the number of particles produced from a conformal scalar field vacuum due to the creation of a gauge cosmic string. We find that the number of particles released in string formation…

High Energy Physics - Theory · Physics 2009-10-30 Bjørn Jensen

The possibility of the cosmic string creation by the vacuum fluctuations of quantum fields in the self-consistent semiclassical theory of gravity is discussed. We use the approximate method for obtaining vacuum expectation value of the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Arkadii Popov