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arXiv 1506.01469astro-ph.CO
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调制预热对暴胀子衰变率变化的限制

Constraints on variations in inflaton decay rate from modulated preheating

Arindam Mazumdar, Kamakshya Prasad Modak

摘要:

调制(p)再加热被认为是在CMB中产生超视界曲率扰动的另一种机制。但是这种机制产生的大的非高斯性和等曲率扰动排除了它作为产生CMB扰动的唯一过程的可接受性。我们研究了这样一种情况,即宇宙微波背景扰动主要是由暴胀过程中暴胀子的量子涨落产生的,但暴胀子与次级标量之间的调制耦合常数影响了预热过程,产生了一些额外的曲率扰动.如果调制标量场被认为是暗物质的候选者,场之间的耦合常数必须被不自然地微调,以保持局域形式的非高斯性和等曲率扰动的幅度在观测极限内;否则,模型的参数必须被严格约束。这些约束意味着调制预热产生的曲率扰动应小于总观测到的CMB扰动的15%。另一方面,如果调制标量场不是暗物质候选者,则模型的参数不能被约束,但是对来自调制预热的曲率扰动的最大量的约束仍然有效。

英文摘要:

Modulated (p)reheating is thought to be an alternative mechanism for producing super-horizon curvature perturbations in CMB. But large non-gaussianity and iso-curvature perturbations produced by this mechanism rule out its acceptability as the sole process responsible for generating CMB perturbations. We explore the situation where CMB perturbations are mostly generated by usual quantum fluctuations of inflaton during inflation, but a modulated coupling constant between inflaton and a secondary scalar affects the preheating process and produces some extra curvature perturbations. If the modulating scalar field is considered to be a dark matter candidate, coupling constant between the fields has to be unnaturally fine tuned in order to keep the local-form non-gaussianity and the amplitude of iso-curvature perturbations within observational limit; otherwise parameters of the models have to be tightly constrained. Those constraints imply that the curvature perturbations generated by modulated preheating should be less than 15% of the total observed CMB perturbations. On the other hand if the modulating scalar field is not a dark matter candidate, parameters of the models could not be constrained, but the constraints on the maximum amount of the curvature perturbations coming from modulated preheating remain valid.

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