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arXiv 1106.0064hep-ph
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轻无菌中微子的极小模型

Minimal models with light sterile neutrinos

A. Donini, P. Hernandez, J. Lopez-Pavon, M. Maltoni

摘要:

我们研究了中微子振荡实验对标准模型(SM)的最小扩展与$n_R$规范单重态费米子(“右手中微子”),可以占中微子质量的约束。我们认为最普遍的耦合SM领域的新领域,特别是那些打破轻子数,我们不假设任何先验层次的质量参数。我们从最低层次的复杂性开始分析这些模型,定义为额外的费米子自由度的数量。最简单的选择,有足够的自由参数在原则上(即两个质量差和两个角度),以解释确认太阳和大气振荡对应于$n_R=1$。这一最小选择被数据排除在外。次最小选择对应于$n_R=2$。我们进行了系统的研究,要求至少有两个中微子的质量差对应于太阳和大气振荡所建立的限制简并马约拉纳群众的全参数空间。我们确定了几种类型的光谱,可以适合长基线反应堆和加速器中微子振荡数据,但未能解释太阳和/或大气数据。仅有的两个解决方案是预期的跷跷板和准狄拉克区域,我们分别设定了马约拉纳质量尺度的下限和上限。太阳中性电流测量数据提供了必要的信息,以限制准狄拉克区域。简要讨论了容纳LSND/MiniBoone和反应堆异常的可能性,以及对无中微子双β衰变和氚β衰变的影响。

英文摘要:

We study the constraints imposed by neutrino oscillation experiments on the minimal extensions of the Standard Model (SM) with $n_R$ gauge singlet fermions ("right-handed neutrinos"), that can account for neutrino masses. We consider the most general coupling to SM fields of the new fields, in particular those that break lepton number and we do not assume any a priori hierarchy in the mass parameters. We proceed to analyze these models starting from the lowest level of complexity, defined by the number of extra fermionic degrees of freedom. The simplest choice that has enough free parameters in principle (i.e. two mass differences and two angles) to explain the confirmed solar and atmospheric oscillations corresponds to $n_R=1$. This minimal choice is shown to be excluded by data. The next-to-minimal choice corresponds to $n_R=2$. We perform a systematic study of the full parameter space in the limit of degenerate Majorana masses by requiring that at least two neutrino mass differences correspond to those established by solar and atmospheric oscillations. We identify several types of spectra that can fit long-baseline reactor and accelerator neutrino oscillation data, but fail in explaining solar and/or atmospheric data. The only two solutions that survive are the expected seesaw and quasi-Dirac regions, for which we set lower and upper bounds respectively on the Majorana mass scale. Solar data from neutral current measurements provide essential information to constrain the quasi-Dirac region. The possibility to accommodate the LSND/MiniBoone and reactor anomalies, and the implications for neutrinoless double-beta decay and tritium beta decay are briefly discussed.

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