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arXiv hep-ph/0409276hep-phastro-phhep-ex
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中微子为什么会发光?--另类

Why Are Neutrinos Light? -- An Alternative

Lawrence J. Hall, Steven J. Oliver

摘要:

我们回顾了最近的建议,中微子是轻的,因为他们的质量是成比例的轻子味对称性破缺的低尺度,f。这种机制是可检验的,因为由此产生的质量为mG的伪戈德斯通玻色子与中微子强烈耦合,影响早期宇宙eV时代的声学振荡,从而产生CMB辐射的峰值。由于总的相对论能量密度的变化以及中微子的散射而不是自由流,特征信号在很宽的(f,m_G)范围内产生。热力学允许对信号进行精确的计算,这样观测不仅可以确认后期中微子的质量机制,而且还可以确定中微子光谱是简并的、倒置的还是分级的,以及中微子是狄拉克的还是马约拉纳的。味对称性也可以给出光无菌状态。如果不育中微子的质量在MeV时代之后开始,那么LSND振荡就可以在不破坏大爆炸核合成的情况下得到解释,而且,由于不育态衰变为较轻的中微子和伪戈德斯通,也不会产生太多热的暗物质。

英文摘要:

We review the recent proposal that neutrinos are light because their masses are proportional to a low scale, f, of lepton flavor symmetry breaking. This mechanism is testable because the resulting pseudo-Goldstone bosons, of mass m_G, couple strongly with the neutrinos, affecting the acoustic oscillations during the eV era of the early universe that generate the peaks in the CMB radiation. Characteristic signals result over a very wide range of (f, m_G) because of a change in the total relativistic energy density and because the neutrinos scatter rather than free-stream. Thermodynamics allows a precise calculation of the signal, so that observations would not only confirm the late-time neutrino mass mechanism, but could also determine whether the neutrino spectrum is degenerate, inverted or hierarchical and whether the neutrinos are Dirac or Majorana. The flavor symmetries could also give light sterile states. If the masses of the sterile neutrinos turn on after the MeV era, the LSND oscillations can be explained without upsetting big bang nucleosynthesis, and, since the sterile states decay to lighter neutrinos and pseudo-Goldstones, without giving too much hot dark matter.

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