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arXiv 0903.2996hep-ph
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一个多体中微子模型的构造与分析

Construction and Analysis of a Many-Body Neutrino model

Ivona Okuniewicz

摘要:

在早期宇宙和超新星等系统中,中微子占总粒子数密度的很大一部分,因此需要考虑中微子自折射。相干中微子-中微子散射被发现在系统的味道演化中发挥作用。传统上,这个问题已经通过假设系统的波函数可以分解为单体状态来分析。然而,在1992年,潘塔列奥内指出,中微子系综一般是一个多体问题,由于非对角贡献的中微子折射率。这个问题直到最近才得到研究。Bell、Rawlinson和Sawyer提出,量子纠缠可能在稠密中微子系统的味道演化中起重要作用。在这篇论文中,我们通过构造一个多体中微子模型来检验单体近似的有效性。中微子系统是由相互作用的自旋系统模拟的,这是弗里德兰和卢纳尔迪尼早期的工作。我们扩展这项工作,通过将模型推广到具有不对称风味组合物的初始状态。我们找到了系统的精确解析解。这项研究揭示了一系列有趣的物理现象,包括半经典行为、量子平衡以及从半经典到纯量子的过渡。此外,这项研究还没有发现任何证据证明对密集中微子系综的单体描述的违反。我们还注意到,我们的分析是有效的任何两个状态系统具有相等的强度相互作用。

英文摘要:

In systems such as the early universe and supernova neutrinos comprise a large fraction of the total particle number density thus one needs to consider neutrino self-refraction. Coherent neutrino-neutrino scattering has been found to play a role in the flavour evolution of the system. Traditionally this problem has been analysed by assuming that the wavefunction of the system can be factorised into one-body states. However in 1992 Pantaleone showed that a neutrino ensemble is in general a many-body problem due to the off-diagonal contribution to the neutrino refractive index. This topic was unexamined until recently. It has been suggested by Bell, Rawlinson and Sawyer that quantum entanglement could play an essential role in the flavour evolution of the dense neutrino system. In this thesis we examine the validity of the one-body approximation by constructing a many-body neutrino model. The neutrino system is modelled by a system of interacting spins following earlier work of Friedland and Lunardini. We extend this work by generalising the model to initial states with asymmetric flavour composition. We find an exact analytical solution to the system. The investigation has revealed an array of interesting physics including semi-classical behaviour, quantum equilibration and a transition from semi-classical to purely quantum regimes. Further, this study has found no evidence for the violation of the one-body description of a dense neutrino ensemble. We also note that our analysis is valid for any two state system with equal strength interactions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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