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arXiv 1304.3262hep-thastro-ph.COgr-qchep-ph
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膜膨胀中的叠加振荡

Superimposed Oscillations in Brane Inflation

Santiago Avila, Jerome Martin, Daniele Steer

备注：
21 pages, 9 figures, references added, minor changes, conclusions unchanged
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摘要：

在正则标量场暴胀中，Starobinsky模型（具有线性势但斜率不连续）的显著之处在于，尽管违反了慢滚，但功率谱和双谱都可以精确地解析计算。两点函数的特点是在大尺度和小尺度上的功率不同，以及其间的小振幅叠加振荡的爆发。出于弦理论模型与坚持膜，我们扩展这种分析狄拉克玻恩因菲尔德（DBI）的通货膨胀，广义慢卷违反在不连续性和快速变化的声速c_s发生。在试图解释非线性动力学项对原始功率谱的振荡特征的影响时，我们证明了所得到的功率谱具有与标准Starobinsky模型显著不同的形状和特征。特别是，功率谱现在在大尺度和小尺度上具有非常相似的尺度不变值，而在中间尺度上，其特征在于更大的振幅和更高的频率叠加振荡。我们还表明，在这个模型中计算非高斯性是一个复杂的，但有趣的任务，因为在立方行动的所有条款现在作出贡献。研究叠加振荡是否可以与普朗克宇宙微波背景（CMB）数据（例如通过解释大尺度普朗克异常）相吻合，同时，小的非高斯性仍然是一个有趣的和开放的可能性。

英文摘要：

In canonical scalar field inflation, the Starobinsky model (with a linear potential but discontinuous slope) is remarkable in that though slow-roll is violated, both the power-spectrum and bi-spectrum can be calculated exactly analytically. The two-point function is characterised by different power on large and small scales, and a burst of small amplitude superimposed oscillations in between. Motivated by string-theory models with stuck branes, we extend this analysis to Dirac Born Infeld (DBI) inflation, for which generalised slow-roll is violated at the discontinuity and a rapid variation in the speed of sound c_s occurs. In an attempt to characterise the effect of non-linear kinetic terms on the oscillatory features of the primordial power-spectrum, we show that the resulting power spectrum has a shape and features which differ significantly from those of the standard Starobinsky model. In particular, the power-spectrum now takes very similar scale invariant values on large and small scales, while on intermediate scales it is characterised by much larger amplitude and higher frequency superimposed oscillations. We also show that calculating non-Gaussianities in this model is a complicated but interesting task since all terms in the cubic action now contribute. Investigating whether the superimposed oscillations could fit to the Planck Cosmic Microwave Background (CMB) data (for instance by explaining the large scale Planck anomalies) with, at the same time, small non-Gaussianities remains an intriguing and open possibility.

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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