Fate of oscillating scalar fields in a thermal bath and their cosmological implications
Fate of oscillating scalar fields in a thermal bath and their cosmological implications
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DOI：
10.1103/physrevd.70.103511
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发表时间：
2004-06
影响因子：
5
通讯作者：
J. Yokoyama
中科院分区：
文献类型：
--
作者：
J. Yokoyama
用非平衡量子场论研究了热浴中相干标量场振荡的弛豫过程。Langevin型运动方程，其中有一个记忆项和加性和乘性噪声项。计算了各种相互作用，如汤川耦合，三体标量相互作用，和双二次相互作用的振荡标量场的耗散率。当背景温度大于振荡频率时，由于Pauli阻塞效应，与费米子相互作用的耗散率被抑制，而与玻色子相互作用的耗散率由于诱导效应被增强.在这两种情况下，我们发现，微物理详细平衡关系驱动的振荡场的热平衡状态。也就是说，对于低动量模式，经典的涨落耗散定理成立，它们松弛到满足均分定律的状态，而高动量模式达到每个量子的数密度由热玻色子分布函数和零点真空贡献组成的状态。将所得的依赖于温度的耗散率应用于暴胀宇宙的再加热晚期。发现在某些情况下，再热温度可能采取与传统估计略有不同的值，并且在更极端的情况下，暴胀子可以耗散其能量而没有导致其衰减的线性相互作用。此外，计算了阿弗莱克-戴恩场在振荡开始时的蒸发率。«少
Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and inmore » an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.« less