Evolution of a non-Abelian cosmic string network

Abstract

We describe a numerical simulation of the evolution of an S 3 cosmic string network which takes fully into account the noncommutative nature of the cosmic string fluxes and the topological obstructions which hinder strings from moving past each other or intercommuting. The influence of initial conditions, string tensions, and other parameters on the network's evolution is explored. Contrary to some previous suggestions, we find no strong evidence of the ''freezing'' required for a string-dominated cosmological scenario. Instead, the results in a broad range of regimes are consistent with the familiar scaling law, i.e., a constant number of strings per horizon volume. The size of this number, however, can vary quite a bit, as can other overall features. There is a surprisingly strong dependence on the statistical properties of the initial conditions. We also observe a rich variety of interesting new structures, such as light string webs stretched between heavier strings, which are not seen in Abelian networks. ͓S0556-2821͑98͒00304-X͔ PACS number͑s͒: 98.80.Cq

Introduction to Cosmic F- and D-Strings

“…If so, its density would come to dominate at the tensions that we are considering. The F-D networks have not yet been simulated, but simulations of comparable networks suggest that they scale, possibly with an enhanced density of strings [97,98,99]. From the discussion above, it follows that one will not directly read off the spectrum (16) from the observations, but there should eventually be enough information to distinguish F-D string networks from other types.…”

Cosmological perturbations in elastic dark energy models

“…One possible realization of the elastic fluid dark energy models is a frustrated network of non-Abelian cosmic strings [17,18,50,51] or domain walls [20,52]. In this section we discuss some basic aspects of these scenarios and make attempts to link them with the earlier sections.…”

“…The metric perturbation is parameterized by h ij = 2H ij , where H ij is decomposed according to (51). In order to compare the elastic fluid with other fluid based models, we use the parameterization of the the energy-momentum tensor used in ref.…”

Scaling laws for nonintercommuting cosmic string networks

“…This leads to the so-called entangled networks [22,23,24]. Again the naive expectation is that they might be conformally frozen, leading to the so-called frustrated networks.…”

“…The scenario of standard intercommuting strings dominating the universe was also discussed [21], but it can never be realized for realistic networks. On the other hand, relatively small numerical simulations [22,23,24] report that linear scaling is reached except in special circumstances.…”