Low-scale leptogenesis and the domain wall problem in models with discrete flavor symmetries
Low-scale leptogenesis and the domain wall problem in models with discrete flavor symmetries
复制标题
具有离散风味对称性的模型中的低尺度轻体发生和域壁问题
DOI：
10.1016/j.physletb.2010.05.073
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发表时间：
2010
影响因子：
4.4
通讯作者：
F. Riva
中科院分区：
文献类型：
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作者：
F. Riva
我们提出了一种新的纤生机制，这种机制在基于离散群A4的风味对称模型中自然实现，其中对称破缺参数也控制重右手中微子的马约拉纳质量。在早期的宇宙中，对于T≤TeV，由于有限的温度贡献，部分对称性被恢复，RH中微子保持无质量，即使在远低于最保守的引力子界限的温度下也能在热平衡中产生。低于这个温度，相变发生，它们变得巨大，从平衡状态衰减，产生必要的轻子不对称。除非对称被普朗克抑制项明确地打破，否则由对称打破产生的畴壁会一直存在到夸克-强子相变，在那里它们会由于QCD异常引起的a4真空之间的小能量分裂而消失。
We propose a new mechanism for leptogenesis, which is naturally realized in models with a flavor symmetry based on the discrete group A4, where the symmetry breaking parameter also controls the Majorana masses for the heavy right-handed (RH) neutrinos. During the early universe, for T≳TeV, part of the symmetry is restored, due to finite temperature contributions, and the RH neutrinos remain massless and can be produced in thermal equilibrium even at temperatures well below the most conservative gravitino bounds. Below this temperature the phase transition occurs and they become massive, decaying out of equilibrium and producing the necessary lepton asymmetry. Unless the symmetry is broken explicitly by Planck-suppressed terms, the domain walls generated by the symmetry breaking survive till the quark–hadron phase transition, where they disappear due to a small energy splitting between the A4vacua caused by the QCD anomaly.