arXiv 2102.077232021-02astro-ph.COhep-ph

轴子弦网络的标度性研究

Approach to scaling in axion string networks

Mark Hindmarsh, Joanes Lizarraga, Asier Lopez-Eiguren, Jon Urrestilla

备注：: 14 pages, 9 figures. v2: Minor changes, matches published version
发表信息：: Phys. Rev. D 103, 103534 (2021)
DOI：: 10.1103/PhysRevD.103.103534

摘要：

通过测量均方根速度$v$和标度平均弦间距$x$，研究了辐射时代轴子弦网络的标度方法。我们找到了很好的证据，在相空间分析中的变量$(x,v)$的固定点，提供了一个强有力的指示，标准缩放正在发生。我们表明，缩放的方法可以很好地描述由两个参数的速度一尺度（VOS）模型，并表明参数的值是不敏感的网络的初始状态。弦的长度通常也用无量纲的弦长度密度$ζ$来表示，它正比于每哈勃体积中弦的哈勃长度。在远离固定点的初始条件的模拟中，$ζ$在半个光交叉时间后仍在发展，这在文献中被解释为长期对数增长。我们表明，我们所有的模拟，即使是那些远离固定点开始，占的VOS模型的渐近线$ζ_*=1.20\pm0.09$（计算从宇宙静止框架中的字符串长度）和$v_* = 0.609\pm 0.014$。

英文摘要：

We study the approach to scaling in axion string networks in the radiation era, through measuring the root-mean-square velocity $v$ as well as the scaled mean string separation $x$. We find good evidence for a fixed point in the phase-space analysis in the variables $(x,v)$, providing a strong indication that standard scaling is taking place. We show that the approach to scaling can be well described by a two parameter velocity-one-scale (VOS) model, and show that the values of the parameters are insensitive to the initial state of the network. The string length has also been commonly expressed in terms of a dimensionless string length density $ζ$, proportional to the number of Hubble lengths of string per Hubble volume. In simulations with initial conditions far from the fixed point $ζ$ is still evolving after half a light-crossing time, which has been interpreted in the literature as a long-term logarithmic growth. We show that all our simulations, even those starting far from the fixed point, are accounted for by a VOS model with an asymptote of $ζ_*=1.20\pm0.09$ (calculated from the string length in the cosmic rest frame) and $v_* = 0.609\pm 0.014$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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英文摘要：

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