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arXiv 1201.4848hep-thastro-ph.COgr-qchep-ph
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暴胀期间重场的重要性

On the importance of heavy fields during inflation

Sebastian Cespedes, Vicente Atal, Gonzalo A. Palma

摘要:

我们研究了两个领域的暴胀模型的动力学特征之间的曲率和isocurvature模式的质量层次。当层次是大的,一个低能量的有效场论(EFT)存在,其中只有曲率模式参与的扰动动力学。在该EFT中,重场在低能量动力学中继续具有重要作用,因为每当多场轨迹在目标空间中经历急转弯时,重场与曲率模式的相互作用降低了它们的声速。在这里,我们分析的一般条件下,EFT仍然是一个可靠的描述曲率模式的线性演化。我们发现,主要的条件包括要求的变化率的转弯的角速度保持抑制相对于重模式的质量。这个绝热条件允许EFT准确地描述了大量的各种情况下,多场轨迹是受急转弯。为了检验这一点,我们分析了几个模型的轮流,并表明,事实上,功率谱获得的原始两个场论和它的单场EFT是相同的绝热条件时,得到满足。特别是,当转弯是尖锐和突然的,他们被发现在功率谱中产生大的功能,准确地再现的EFT。

英文摘要:

We study the dynamics of two-field models of inflation characterized by a hierarchy of masses between curvature and isocurvature modes. When the hierarchy is large, a low energy effective field theory (EFT) exists in which only curvature modes participate in the dynamics of perturbations. In this EFT heavy fields continue to have a significant role in the low energy dynamics, as their interaction with curvature modes reduces their speed of sound whenever the multi-field trajectory is subject to a sharp turn in target space. Here we analyze under which general conditions this EFT remains a reliable description for the linear evolution of curvature modes. We find that the main condition consists on demanding that the rate of change of the turn's angular velocity stays suppressed with respect to the masses of heavy modes. This adiabaticity condition allows the EFT to accurately describe a large variety of situations in which the multi-field trajectory is subject to sharp turns. To test this, we analyze several models with turns and show that, indeed, the power spectra obtained for both the original two-field theory and its single-field EFT are identical when the adiabaticity condition is satisfied. In particular, when turns are sharp and sudden, they are found to generate large features in the power spectrum, accurately reproduced by the EFT.

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