arXiv 1111.66902011-11hep-ph

多个右手中微子的大混合角

Large Mixing Angles From Many Right-Handed Neutrinos

Brian Feldstein, William Klemm

备注：: 22 pages, 7 figures; v2: rare bug in diagonalization algorithm corrected- little quantitative impact on results
DOI：: 10.1103/PhysRevD.85.053007

摘要：

通过跷跷板机制可以很好地理解中微子质量的微小性，即利用中微子和其他费米子之间的关键质的区别：右手中微子是规范单线态，因此可能具有大的马约拉纳质量。然而，标准跷跷板机制并没有解决与夸克和带电轻子相比，中微子质量明显缺乏层次的问题，也没有解决与CKM矩阵的小角度相比，大的轻子混合角的问题。在本文中，我们将证明右手中微子的单线态性质可以进一步利用，以解决这些剩余的问题：与具有规范相互作用的粒子不同，其数量受到异常抵消的限制，规范单线态粒子的数量基本上是不确定的。如果在高能量下存在大量的规范单态费米子--例如，各种弦结构所暗示的--那么有效的低能中微子质量矩阵可以被确定为许多不同的汤川耦合的总和，其中最大的是最重要的。这可以减少层次，并导致大的混合角度。假设一个统计分布的基本参数，我们将表明，这种情况下导致一个很好的适合低能现象，只有一些定性的假设，由已知的夸克和轻子质量的指导。该方案导致预测的正常层次的中微子质量，和一个值的|m_ee|质量矩阵元约1-6 meV。

英文摘要：

A beautiful understanding of the smallness of the neutrino masses may be obtained via the seesaw mechanism, whereby one takes advantage of the key qualitative distinction between the neutrinos and the other fermions: right-handed neutrinos are gauge singlets, and may therefore have large Majorana masses. The standard seesaw mechanism, however, does not address the apparent lack of hierarchy in the neutrino masses compared to the quarks and charged leptons, nor the large leptonic mixing angles compared to the small angles of the CKM matrix. In this paper, we will show that the singlet nature of the right-handed neutrinos may be taken advantage of in one further way in order to solve these remaining problems: Unlike particles with gauge interactions, whose numbers are constrained by anomaly cancellation, the number of gauge singlet particles is essentially undetermined. If large numbers of gauge singlet fermions are present at high energies - as is suggested, for example, by various string constructions - then the effective low energy neutrino mass matrix may be determined as a sum over many distinct Yukawa couplings, with the largest ones being the most important. This can reduce hierarchy, and lead to large mixing angles. Assuming a statistical distribution of fundamental parameters, we will show that this scenario leads to a good fit to low energy phenomenology, with only a few qualitative assumptions guided by the known quark and lepton masses. The scenario leads to predictions of a normal hierarchy for the neutrino masses, and a value for the |m_ee| mass matrix element of about 1-6 meV.

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英文摘要：

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