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arXiv 1409.8409hep-phastro-ph.COhep-th
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公理景观与自然暴胀

Axion Landscape and Natural Inflation

Tetsutaro Higaki, Fuminobu Takahashi

摘要:

多个轴子在各种移位对称性破缺项的存在下形成一个景观。永恒的暴胀填充了轴子景观,通过气泡成核不断创造新的宇宙。慢卷暴胀发生在隧穿事件之后,如果一个非常平坦的方向与超普朗克衰变常数出现由于对齐机制。我们研究了轴子景观场景中的真空结构以及可能的暴胀动力学,发现暴胀子动力学是由自然暴胀或多自然暴胀给出的。在衰减常数较大的情况下,可以用二次混沌暴胀来近似,但在暴胀持续时间较短的情况下,二次混沌暴胀是不利的。因此,如果谱指数和张量标量比与二次混沌暴胀不同,则可能存在可观察到的气泡成核痕迹。此外,暴胀子势的小调制的存在是轴子景观中的一个共同特征,它产生了一个相当大的,几乎恒定运行的标量谱指数在CMB尺度。如果某些轴子与无质量的规范场耦合,也可以产生等边型的非高斯性。

英文摘要:

Multiple axions form a landscape in the presence of various shift symmetry breaking terms. Eternal inflation populates the axion landscape, continuously creating new universes by bubble nucleation. Slow-roll inflation takes place after the tunneling event, if a very flat direction with a super-Planckian decay constant arises due to the alignment mechanism. We study the vacuum structure as well as possible inflationary dynamics in the axion landscape scenario, and find that the inflaton dynamics is given by either natural or multi-natural inflation. In the limit of large decay constant, it is approximated by the quadratic chaotic inflation, which however is disfavored if there is a pressure toward shorter duration of inflation. Therefore, if the spectral index and the tensor-to-scalar ratio turn out to be different from the quadratic chaotic inflation, there might be observable traces of the bubble nucleation. Also, the existence of small modulations to the inflaton potential is a common feature in the axion landscape, which generates a sizable and almost constant running of the scalar spectral index over CMB scales. Non-Gaussianity of equilateral type can also be generated if some of the axions are coupled to massless gauge fields.

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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