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arXiv 2012.05354hep-ph
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准简并中微子轻生过程中的混合和振荡中的CP破坏

CP violation in mixing and oscillations for leptogenesis with quasi-degenerate neutrinos

J. Racker

摘要:

研究了准简并中微子重子生成模型的CP破坏来源。我们的方法是在中微子振荡的量子场论模型中使用重整化传播子,密切关注么正性要求。从这样得到的轻子数破坏过程的概率,我们导出了轻子不对称性随时间演化的源项。源项的贡献可以通过混合、振荡和两者之间的干扰来识别为CP破坏。由于这个源项不涉及初始或最终状态的不稳定粒子的过程,也不需要计算中微子的数密度,因此不需要减去真实的中间态。在平衡态下,由于混合和振荡中的CP破坏项之间的抵消,源项为零,这是酉性和CPT不变性所要求的。计算是在一个简单的标量玩具模型中完成的,并且在质量差上的衰变宽度中,在一阶对角化了图中的传播子。我们还评论的干扰项,这是温和的顺序,我们的工作,但似乎变得更加重要,随着退化。

英文摘要:

We study the sources of CP violation for baryogenesis models with quasi-degenerate neutrinos. Our approach is to use the renormalized propagator in a quantum field theory model of neutrino oscillations, paying close attention to unitarity requirements. From the probabilities of lepton number violating processes obtained in this way, we derive a source term for the time evolution of the lepton asymmetry. The source term has contributions that can be identified with CP violation from mixing, oscillations and interference between both. Given that this source term does not involve processes with unstable particles in the initial or final states, neither does it require to calculate number densities of neutrinos, no subtraction of real intermediate states must be performed. In equilibrium the source term is null, as demanded by unitarity and CPT invariance, due to a cancellation between the terms coming from CP violation in mixing and oscillations. The calculations are done in a simple scalar toy model, and the resummed propagator is diagonalized at first order in the decay widths over the mass difference. We also comment on the effect of the interference term, which is mild at the order we work, but seems to become more important with increasing degeneracy.

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