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Cosmic string networks are the best motivated relics of cosmological phase transitions, being unavoidable in many physically plausible extensions of the Standard Model. Most studies, including those providing constraints from and forecasts…

High Energy Physics - Phenomenology · Physics 2024-06-07 F. C. N. Q. Pimenta , C. J. A. P. Martins

We continue our studies of the evolution and cosmological consequences of current-carrying cosmic string networks, described by a charge-velocity-dependent one scale (CVOS) model. We present a detailed calculation of the effects of these…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-23 I. Yu. Rybak , C. J. A. P. Martins , Patrick Peter , E. P. S. Shellard

We apply a recently developed formalism to study the evolution of a current-carrying string network under the simple but generic assumption of a linear equation of state. We demonstrate that the existence of a scaling solution with…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 C. J. A. P. Martins , Patrick Peter , I. Yu. Rybak , E. P. S. Shellard

We present an extension of the velocity-dependent one-scale model for cosmic string evolution, which is suitable for describing the evolution of local and global monopole networks. We discuss the key dynamical features that need to be…

High Energy Physics - Phenomenology · Physics 2009-11-13 C. J. A. P. Martins , A. Achucarro

We investigate the velocity-dependent one-scale (VOS) model to the case of one cosmic F-string and two D-strings as color flux tubes in pure Spin($4N$) gauge theory. We analytically calculate the scaling string density as a function of the…

High Energy Physics - Phenomenology · Physics 2025-12-23 Kazuto Nakamura , Masaki Yamada

We study the formation and evolution of an interconnected string network in large-scale field-theory numerical simulations, both in flat spacetime and in expanding universe. The network consists of gauge U(1) strings of two different kinds…

High Energy Physics - Theory · Physics 2008-11-26 Jon Urrestilla , Alexander Vilenkin

The velocity-dependent `one-scale' model of Martins and Shellard is used to study the evolution of a cosmic string network (and the corresponding loop population) in open universes. It is shown that in this case there is no linear scaling…

Astrophysics · Physics 2009-10-30 C. J. A. P. Martins

We study how the presence of world-sheet currents affects the evolution of cosmic string networks, and their impact on predictions for the cosmic microwave background (CMB) anisotropies generated by these networks. We provide a general…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-21 I. Yu. Rybak , A. Avgoustidis , C. J. A. P. Martins

We use the Velocity-dependent One Scale Model for topological defect evolution to explore and classify the possible scaling solutions for string networks with time-varying tension, in cosmological and non-cosmological settings and under two…

High Energy Physics - Phenomenology · Physics 2026-02-24 C. S. C. M. Coelho , A. -L. Y. Gschrey , C. J. A. P. Martins

We continue our exploration of the wiggly generalisation of the Velocity-Dependent One Scale Model for cosmic strings, through the study of its allowed asymptotic scaling solutions. We extend the work of a previous paper [Almeida $\&$…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-09 A. Almeida , C. J. A. P. Martins

We discuss the cosmological evolution of cosmic strings with time-dependent tension. We show that, in the case that the tension changes as a power of time, the cosmic string network obeys the scaling solution: the characteristic scale of…

High Energy Physics - Phenomenology · Physics 2009-11-11 Masahide Yamaguchi

I use a combination of state-of-the-art numerical simulations and analytic modelling to discuss the scaling properties of cosmic defect networks, including superstrings. Particular attention is given to the role of extra degrees of freedom…

High Energy Physics - Phenomenology · Physics 2015-06-17 C. J. A. P. Martins

We discuss friction-dominated vortex-string evolution using a new analytic model recently developed by the authors. By treating the average string velocity, as well as the characteristic lengthscale, as dynamical variables, we can provide a…

Condensed Matter · Physics 2009-10-28 C. J. A. P. Martins , E. P. S. Shellard

Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-01 R. P. L. Azevedo , C. J. A. P. Martins

We extend and develop our previous work on the evolution of a network of cosmic strings. The new treatment is based on an analysis of the probability distribution of the end-to-end distance of a randomly chosen segment of left-moving string…

High Energy Physics - Phenomenology · Physics 2016-09-01 Daren Austin , E. J. Copeland , T. W. B. Kibble

Quantitative studies of the evolution and cosmological consequences of networks of cosmic strings (or other topological defects) require a combination of numerical simulations and analytic modeling with the velocity-dependent one-scale…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-19 J. R. C. C. C. Correia , C. J. A. P. Martins

We describe a numerical simulation of the evolution of an $S_3$ cosmic string network which takes fully into account the non-commutative nature of the cosmic string fluxes and the topological obstructions which hinder strings from moving…

Astrophysics · Physics 2009-10-30 Patrick N. McGraw

A synthesis of previous work done on the microscopic structure of cosmic strings in realistic models is made and reveals that strings are expected to be not only superconducting in the sense of Witten, but also generically current-carrying,…

High Energy Physics - Phenomenology · Physics 2009-10-28 Anne-Christine Davis , Patrick Peter

We clarify the quantitative nature of the cosmological evolution of a global string network, that is, the energy density, peculiar velocity, velocity squared, Lorentz factor, formation rate of loops, and emission rate of Nambu-Goldstone…

High Energy Physics - Phenomenology · Physics 2009-11-07 Masahide Yamaguchi , Jun'ichi Yokoyama

It has recently been realised that strings with time-dependent tensions exhibit interesting dynamics; in particular, when the tension decreases loops of string can grow and possibly percolate. We extend previous analytic studies of strings…

High Energy Physics - Theory · Physics 2026-01-09 Hubert Lau Sze Chun , Joseph Conlon