论文标题
高分辨率u（1）$ \ times $ u（1）模拟中的多重性字符串
Multitension strings in high-resolution U(1)$\times$U(1) simulations
论文作者
论文摘要
拓扑缺陷是早期宇宙相过渡的化石遗物，宇宙弦是最好的动机例子。虽然在大多数情况下，人们研究了Nambu-Goto或Abelian-Higgs字符串，但人们还期望宇宙学上现实的字符串在其世界表格中应该具有额外的自由度，一个具体的例子是IIB型超链式理论的超弦。 Here we continue the scientific exploitation of our recently developed multi-GPU field theory cosmic strings code to study the evolution of U(1)$\times$U(1) multitension networks, which are a numerically convenient proxy: these contain two lowest-tension strings networks able to interact and form bound states, providing a convenient first approximation to the behaviour expected from cosmic superstrings. （...）到目前为止，我们依靠该模型的最大现场理论模拟，特别是$ 4096^3 $，$ΔX= 0.5 $ box。我们提供了通过完整且自洽的相关长度和速度诊断的完整且一致的缩放弦的缩放证据。我们还发现，与缩放行为一致的结合状态段的平均长度线性增长。 （在先前报道的较低分辨率模拟中，这种行为仅在精心设计的初始条件下被鉴定出来，富含这些细分市场。）最后，尽管没有证据表明网络进化的早期阶段形成大量的结合状态，但我们确实提供了暂定的证据，证明了结合状态的分数的无效恒定值，而这种值在辐射和辐射中是不同的。我们的工作表明，我们的GPU加速现场理论代码可以通过成功扩展到简单的Abelian-Higgs近似，并可以对现实的字符串网络及其观察性签名进行详细研究。
Topological defects are a fossil relic of early Universe phase transitions, with cosmic strings being the best motivated example. While in most cases one studies Nambu-Goto or Abelian-Higgs strings, one also expects that cosmologically realistic strings should have additional degrees of freedom in their worldsheets, one specific example being superstrings from Type IIB superstring theory. Here we continue the scientific exploitation of our recently developed multi-GPU field theory cosmic strings code to study the evolution of U(1)$\times$U(1) multitension networks, which are a numerically convenient proxy: these contain two lowest-tension strings networks able to interact and form bound states, providing a convenient first approximation to the behaviour expected from cosmic superstrings. (...) We rely on the largest field theory simulations of this model so far, specifically $4096^3$, $Δx = 0.5$ boxes. We present robust evidence of scaling for the lightest strings, measured through a complete and self-consistent set of correlation length and velocity diagnostics. We also find a linearly growing average length of the bound state segments, consistent with a scaling behaviour. (In previously reported lower-resolution simulations, such behaviour had only been identified with carefully engineered initial conditions, rich in those segments.) Finally, while we see no evidence of a large population of bound states forming at early stages of the network evolution, we do present tentative evidence for an asymptotic constant value of the fraction of bound states, with this value being different in the radiation and the matter eras. Our work demonstrates that our GPU-accelerated field theory code can by successfully extended beyond the simple Abelian-Higgs approximation, and enables future detailed studies of realistic string networks and of their observational signatures.
