Towards the theory of reheating after inflation
Towards the theory of reheating after inflation
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DOI：
10.1103/physrevd.56.3258
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发表时间：
1997-09-15
影响因子：
5
通讯作者：
Starobinsky, AA
中科院分区：
文献类型：
--
作者：
Kofman, L;Linde, A;Starobinsky, AA
暴胀后的再加热是由于振荡暴胀子场产生粒子而发生的。在本文中，我们简要地描述了微扰的方法，再加热，然后集中在微扰理论之外的影响。它们与参量共振阶段有关，我们称之为预热。如果暴胀子场振荡的初始振幅足够大，它可能发生在膨胀的宇宙中。我们研究了一个简单的模型，一个大质量暴胀子场与另一个标量场耦合，相互作用项为g（2）phi（2）chi（2）。该模型的参数共振范围很广。它以一种非常不寻常的随机方式发生，这与忽略宇宙膨胀时的参量共振完全不同。与振荡暴胀子场相互作用的量子场经历了一系列的反冲，由于宇宙的快速膨胀，这些反冲的相位彼此不相关。尽管这个过程具有随机性，但它导致了场chi波动的指数增长。我们称这个过程为随机共振。我们发展的预热理论考虑到宇宙的膨胀和产生的粒子的反反应，包括再散射的影响。这项研究扩展了我们以前对充气后再加热的研究。我们证明了产生的粒子对有效势V（phi）的贡献不是与phi（2）成比例，而是与\phi\成比例。预热过程可以分为几个不同的阶段。在第一阶段，所产生的粒子的反反应并不重要。在第二阶段，反反应增加了暴胀子场的振荡频率，这使得该过程比以前更有效。然后，与chi粒子对振荡暴胀子场的散射有关的效应终止了共振。我们计算了预热过程中产生的粒子数密度n（chi）及其量子涨落[chi（2）]，并考虑了所有的反反应效应。这使我们能够找到质量和耦合常数的范围，可以有有效的预热。特别是，在某些条件下，这个过程可能会产生质量比暴胀子场的质量大得多的粒子。
Reheating after inflation occurs due to particle production by the oscillating inflaton field. In this paper we briefly describe the perturbative approach to reheating, and then concentrate on effects beyond the perturbation theory. They are related to the stage of parametric resonance, which we call preheating. It may occur in an expanding universe if the initial amplitude,of oscillations of the inflaton field is large enough. We investigate a simple model of a massive inflaton field phi coupled to another scalar field chi with the interaction term g(2) phi(2) chi(2). Parametric resonance in this model is very broad. It occurs in a very unusual stochastic manner, which is quite different from parametric resonance in the case when the expansion of the universe is neglected. Quantum fields interacting with the oscillating inflaton field experience a series of kicks which, because of the rapid expansion of the universe, occur with phases uncorrelated to each other. Despite the stochastic nature of the process, it leads to exponential growth of fluctuations of the field chi. We call this process stochastic resonance. We develop the theory of preheating taking into account the expansion of the universe and back reaction of produced particles, including the effects of rescattering. This investigation extends our previous study of reheating after inflation. We show that the contribution of the produced particles to the effective potential V(phi) is proportional not to phi(2), as is usually the case, but to \phi\. The process of preheating can be divided into several distinct stages. In the first stage the back reaction of created particles is not important. In the second stage back reaction increases the frequency of oscillations of the inflaton field, which makes the process even more efficient than before. Then the effects related to scattering of chi particles on the oscillating inflaton field terminate the resonance. We calculate the number density of particles n(chi) produced during preheating and their quantum fluctuations [chi(2)] with all back reaction effects taken into account. This allows us to find the range of masses and coupling constants for which one can have efficient preheating. In particular, under certain conditions this process may produce particles with a mass much greater than the mass of the inflaton field.