arXiv 1407.35442014-07-14hep-phastro-ph.COhep-th

基于BICEP2的简单膜世界暴胀模型

Simple brane-world inflationary models in light of BICEP2

Nobuchika Okada, Satomi Okada

备注：: 25 pages, 8 figures, 4 tables

摘要：

受BICEP 2合作组最近公布的CMB $B$模式观测的启发，我们研究了Randall-Sundrum膜世界宇宙学中的简单暴胀模型。膜世界宇宙学效应改变了暴胀预言的光谱指数（$n_s$）和张量标量比（$r$），而不是标准宇宙学中得到的结果。特别是，张量-标量比在第5维的存在下得到增强，并且在标准宇宙学中预测小$r$值的简单暴胀模型可以产生与BICEP 2结果$r=0.2^{+0.07}_{-0.05}$兼容的$r$值。在不久的将来，BICEP 2结果的确认和对$n_s$和$r$的更精确测量使我们能够约束膜世界场景的5维普朗克质量（$M_5$）。我们还讨论了后暴胀的情况下，即通过暴胀衰变到标准模型粒子的宇宙再加热。当我们要求暴胀模型的可重整化性时，暴胀子只与标准模型场中的Higgs二重态耦合，通过它发生再加热过程。如果$M_5$低至$10^6$ GeV，暴胀子的质量变为${\cal O}$（100 GeV），假设暴胀预测与BICEP 2和普朗克的结果一致。这种轻暴胀子通过与希格斯偶态的耦合对电弱尺度的唯象学产生了一定的影响。

英文摘要：

Motivated by the recent CMB $B$-mode observation announced by the BICEP2 collaboration, we study simple inflationary models in the Randall-Sundrum brane-world cosmology. Brane-world cosmological effects alter the inflationary predictions of the spectral index ($n_s$) and the tensor-to-scalar ratio ($r$) from those obtained in the standard cosmology. In particular, the tensor-to-scalar ratio is enhanced in the presence of the 5th dimension, and simple inflationary models which predict small $r$ values in the standard cosmology can yield $r$ values being compatible with the BICEP2 result, $r=0.2^{+0.07}_{-0.05}$. Confirmation of the BICEP2 result and more precise measurements of $n_s$ and $r$ in the near future allow us to constrain the 5-dimensional Planck mass ($M_5$) of the brane-world scenario. We also discuss the post inflationary scenario, namely, reheating of the universe through inflaton decay to the Standard Model particles. When we require the renormalizability of the inflationary models, the inflaton only couples with the Higgs doublet among the Standard Model fields, through which reheating process occurs. If $M_5$ is as low as $10^6$ GeV, the mass of inflaton becomes of ${\cal O}$(100 GeV), providing the inflationary predictions being consistent with the BICEP2 and Planck results. Such a light inflaton has some impacts on phenomenology at the electroweak scale through the coupling with the Higgs doublet.

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英文摘要：

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