宇宙微波背景中重标量场的共振特征
Resonant Signatures of Heavy Scalar Fields in the Cosmic Microwave Background
摘要：
研究了在暴胀过程中，质量超过哈勃尺度的重标量场通过其背景振荡与暴胀子涨落之间的参量共振，在宇宙微波背景（CMB）温度各向异性功率谱中留下不可忽略的信号的可能性.通过假设重标量场与暴胀子导数耦合，我们证明了共振可以是有效的，而不会破坏慢卷暴胀。由共振调制的原始功率谱在特定尺度上具有尖锐的峰值，并且可能是在CMB的角功率谱中观察到的异常的起源。在某些参数值下，调制谱比简单的幂律谱能更好地拟合观测数据，但拟合的改善程度不够大，因此还需要其它观测（如非高斯性）来证实CMB异常是由重标量场的共振效应引起的。共振签名可以提供一个机会来观察暴胀过程中的重自由度，并提高我们对暴胀背后的物理学的理解。
英文摘要：
We investigate the possibility that a heavy scalar field, whose mass exceeds the Hubble scale during inflation, could leave non-negligible signatures in the Cosmic Microwave Background (CMB) temperature anisotropy power spectrum through the parametric resonance between its background oscillations and the inflaton fluctuations. By assuming the heavy scalar field couples with the inflaton derivatively, we show that the resonance can be efficient without spoiling the slow-roll inflation. The primordial power spectrum modulated by the resonance has a sharp peak at a specific scale and could be an origin of the anomalies observed in the angular power spectrum of the CMB. In some values of parameters, the modulated spectrum can fit the observed data better than the simple power-law power spectrum, though the resultant improvement of the fit is not large enough and hence other observations such as non-Gaussianity are necessary to confirm that the CMB anomalies are originated from the resonant effect of the heavy scalar field. The resonant signatures can provide an opportunity to observe heavy degrees of freedom during inflation and improve our understanding of physics behind inflation.
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