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arXiv 0705.4149hep-ph
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宇宙学的QCD相变发生了什么?

What happened to the Cosmological QCD Phase Transition?

W-Y. P. Hwang

摘要:

早期宇宙中可能发生了一级相变,这一设想为我们提供了宇宙学中最有趣和最吸引人的问题之一。事实上,在相变中释放的潜热或能量所起的作用是非常重要的,并可能导致一些令人惊讶的重要结果。在本文中,我们认为宇宙学QCD相变是一级相变,它发生在10^(-5)秒和10^(-4)秒之间的时间,或在大约150 MeV的温度下,并解释了夸克和胶子在强子内的禁闭。为了得到这个方案的本质,我们可以将真实的QCD真空近似为一个简并的θ-真空,必要时,我们试图通过一个具有自发对称性破缺的复标量场来有效地模拟它。我们研究如何以及何时“粘贴”或“修补”域壁形成,多久这样的墙从长远来看,我们相信,暗物质的显着部分可以占在这样的域壁结构及其残余。当然,宇宙学QCD相变的发生方式使得与重子和许多其他色单态物体相关的假真空没有消失(也就是说,使用袋模型语言,重子存在半径为1.0费米的袋)--但是假真空中剩余的能量可以忽略不计。假真空向真真空转化所释放出的潜在能量,在短期内以“粘贴”或“修补”的畴壁形式出现,以及它们众多的演化对象,应该使“辐射主导”时代或“物质主导”时代的概念得到重新审视。

英文摘要:

The scenario that some first-order phase transitions may have taken place in the early Universe offers us one of the most intriguing and fascinating questions in cosmology. Indeed, the role played by the latent "heat" or energy released in the phase transition is highly nontrivial and may lead to some surprising, important results. In this paper, we take the wisdom that the cosmological QCD phase transition, which happened at a time between 10^(-5) sec and 10^(-4) sec or at the temperature of about 150 MeV and accounts for confinement of quarks and gluons to within hadrons, would be of first order. To get the essence out of the scenario, it is sufficient to approximate the true QCD vacuum as one of degenerate theta-vacua and when necessary we try to model it effectively via a complex scalar field with spontaneous symmetry breaking. We examine how and when "pasted" or "patched" domain walls are formed, how long such walls evolve in the long run, and we believe that the significant portion of dark matter could be accounted for in terms of such domain-wall structure and its remnants. Of course, the cosmological QCD phase transition happened in the way such that the false vacua associated with baryons and many other color-singlet objects did not disappear (that is, using the bag-model language, there are bags of radius 1.0 fermi for the baryons) - but the amount of the energy remained in the false vacua is negligible. The latent energy released due to the conversion of the false vacua to the true vacua, in the form of "pasted" or "patched" domain walls in the short run and their numerous evolved objects, should make the concept of the "radiation-dominated" epoch, or of the "matter-dominated" epoch to be re-examined.

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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