Cosmic string networks are expected to form in early Universe phase transitions via the Kibble mechanism and are unavoidable in several Beyond the Standard Model theories. While most predictions of observational signals of string networks assume featureless Abelian-Higgs or Nambu-Goto string networks, in many such extensions the networks can carry additional degrees of freedom, including charges and currents; these are often generically known as superconducting strings. All such degrees of freedom can impact the evolution of the networks and therefore their observational signatures. We report on the results of 2048 field theory simulations of the evolution of a current-carrying network of strings, highlighting the different scaling behaviours of the network in the radiation and matter eras. We also report the first numerical measurements of the coherence length scales for the charge and current and of the condensate equation of state, and show that the latter mainly depends on the expansion rate, with chirality occurring for the matter era. Qualitatively, the fact that the matter era is the optimal expansion rate for these networks to reach scaling is in agreement with recent analytic modelling.

中文翻译：

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载流弦网络的演变


宇宙弦网络预计会通过基布尔机制在早期宇宙相变中形成，并且在一些超越标准模型理论中是不可避免的。虽然大多数对弦网络观测信号的预测都假设无特征的阿贝尔-希格斯或南部-后藤弦网络，但在许多此类扩展中，网络可以携带额外的自由度，包括电荷和电流；这些通常被称为超导弦。所有这些自由度都会影响网络的演化，从而影响它们的观测特征。我们报告了 2048 个载流弦网络演化的场论模拟结果，强调了网络在辐射和物质时代的不同尺度行为。我们还报告了电荷和电流的相干长度尺度以及凝聚态方程的首次数值测量，并表明后者主要取决于膨胀率，而手性发生在物质时代。定性地讲，物质时代是这些网络达到规模化的最佳扩张率，这一事实与最近的分析模型是一致的。