论文标题
来自振荡标量场的粒子产生和Boltzmann方程的一致性
Particle Production from Oscillating Scalar Field and Consistency of Boltzmann Equation
论文作者
论文摘要
Boltzmann方程在粒子宇宙学中在研究各种粒子的分布函数的演变（也称为职业数字）中起着重要作用。对于标量冷凝$ ϕ $衰减到一对标量粒子中（称为$χ$）的情况，当$χ$的职业数量在所谓的窄谐振方案中，$χ$的职业数量也很大，玻尔兹曼方程也可能无法很好地描述系统。我们研究颗粒的产生，包括由于最终状态粒子的占用数量，称为刺激的发射或参数共振。根据量子场理论（QFT），我们得出了一组方程，该方程直接控制$χ$的分布函数的演变。比较QFT计算的结果和来自Boltzmann方程的结果，在某些情况下，我们发现了不合述。特别是，在不断扩展的宇宙中，基于QFT的$χ$的职业数量可能与Boltzmann方程的数量级不同。我们还讨论了基于QFT和Boltzmann方程的演化方程之间的可能关系。
Boltzmann equation plays important roles in particle cosmology in studying the evolution of distribution functions (also called as occupation numbers) of various particles. For the case of the decay of a scalar condensation $ϕ$ into a pair of scalar particles (called $χ$), we point out that the system may not be well described by the Boltzmann equation when the occupation number of $χ$ becomes large even in the so-called narrow resonance regime. We study the particle production including the possible enhancement due to a large occupation number of the final state particle, known as the stimulated emission or the parametric resonance. Based on the quantum field theory (QFT), we derive a set of equations which directly govern the evolution of the distribution function of $χ$. Comparing the results of the QFT calculation and those from the Boltzmann equation, we find non-agreements in some cases. In particular, in the expanding Universe, the occupation number of $χ$ based on the QFT may differ by many orders of magnitude from that from the Boltzmann equation. We also discuss a possible relation between the evolution equations based on the QFT and the Boltzmann equation.
