标量凝聚体衰变的时间演化
Time evolution of scalar condensate decay
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中文总结 AI 辅助
本文通过数值追踪子粒子相密度，研究标量凝聚体衰变中参数共振结果向费曼图结果的趋近过程，发现最低阶不稳定带主导总衰变宽度，并用拉比模型解释玻色子与费米子情形的差异。
中文摘要 AI 辅助
一个在空间中相干振荡并通过产生子粒子而衰变的标量场，在宇宙学中扮演着重要角色。最近的研究表明，在长时间尺度下，参数共振方法和费曼图方法对玻色子子粒子给出的衰变率相同。我们通过数值追踪子粒子相密度的随时间演化，研究了参数共振结果如何趋近于这一渐近值。在窄共振区域，我们观察到不同不稳定带之间存在差异。最低阶不稳定带在数十个标量振荡周期内趋近于费曼图结果，而高阶不稳定带的趋近过程还依赖于标量与子粒子之间的耦合。这意味着总衰变宽度（在微扰论中最低阶不稳定带对其贡献最为主要）也独立于耦合而趋近于费曼图结果。为证实这一点，我们考虑了一个更简单且可解析求解的量子力学模型：拉比模型。在玻色子拉比模型中，参数共振和费曼图结果在所有时间都彼此一致。另一方面，在费米子拉比模型中，它们在长时间尺度下不一致。这种差异可归因于玻色子增强与泡利阻塞。
英文摘要
A scalar field, which oscillates coherently over the space and decays through production of daughter particles, plays an important role in cosmology. It was recently shown that the parametric-resonance and Feynman-diagrammatic approaches give the same decay rate for a Bosonic daughter particle at a large time duration. We study how the parametric-resonance result approaches to this asymptotic value, by numerically following the time evolution of the phase density of the daughter particle. We see a difference among different instability bands in the narrow-resonance regime. The lowest-order instability band approaches to the Feynman-diagrammatic result in tens of scalar oscillation periods, while the high-order instability bands approach dependently also on a coupling between the scalar and daughter particles. This would infer that the total decay width, to which the lowest-order instability band contributes most dominantly in the perturbation theory, approaches to the Feynman-diagrammatic result also independently of the coupling. To confirm it, we consider a simpler and analytically solvable quantum mechanical model: Rabi models. In the Bosonic Rabi model, the parametric-resonance and Feynman-diagrammatic results agree with each other for all the time. On the other hand, in the Fermionic Rabi model, they disagree at a large time duration. This difference would be attributed to Bose enhancement vs Pauli blocking.
发表机构
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw（华沙大学物理学院理论物理研究所）
- National Institute of Technology, Tsuruoka College（国立技术筑冈学院）
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