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arXiv 1706.02456hep-ph
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具有普适跷跷板的极小左右对称模型中的无中子双β衰变

Neutrinoless double beta decay in minimal left-right symmetric model with universal seesaw

Debasish Borah, Arnab Dasgupta, Sudhanwa Patra

摘要:

本文详细讨论了基于$SU(2)_L \times SU(2)_R \times U(1)_{B-L}$型规范对称性的左右对称模型中的无中微子双β衰变$(0νββ)$以及$SU(3)_L \times SU(3)_R \times U(1)_{X}$模型中的费米子质量(包括中微子质量)是通过一种普适的跷跷板机制产生的.我们发现,一个或多个右手中微子可以轻到几个keV,如果左右对称性破缺发生在几个TeV到100 TeV的范围内。有了这样的轻右手中微子,我们进行了详细的研究新的物理贡献$0νββ$和约束模型参数从最新的实验约束这样一个罕见的衰变过程。我们发现,在这样的情况下,新的物理贡献$0νββ$,特别是重轻中微子混合图,可以单独饱和现有的实验界限,但它们的贡献总$0νββ$半衰期相互抵消由于总$6\times 6$质量矩阵的么正性。因此,对半衰期的有效贡献来自纯左中微子和纯右中微子与规范玻色子介导图。我们发现,参数空间饱和的$0νββ$界限仍然允许从最新的实验界限带电轻子味违反衰变像$μ\rightarrow e γ$。最后我们引入了宇宙学和超新星的边界来约束模型的参数空间。

英文摘要:

We present a detailed discussion on neutrinoless double beta decay $(0νββ)$ within left-right symmetric models based on the gauge symmetry of type $SU(2)_L \times SU(2)_R \times U(1)_{B-L}$ as well as $SU(3)_L \times SU(3)_R \times U(1)_{X}$ where fermion masses including that of neutrinos are generated through a universal seesaw mechanism. We find that one or more of the right-handed neutrinos could be as light as a few keV if left-right symmetry breaking occurs in the range of a few TeV to 100 TeV. With such light right-handed neutrinos, we perform a detailed study of new physics contributions to $0νββ$ and constrain the model parameters from the latest experimental bound on such a rare decay process. We find that the new physics contribution to $0νββ$ in such a scenario, particularly the heavy-light neutrino mixing diagrams, can individually saturate the existing experimental bounds, but their contributions to total $0νββ$ half-life cancels each other due to unitarity of the total $6\times 6$ mass matrix. The effective contribution to half-life therefore, arises from the purely left and purely right neutrino and gauge boson mediated diagrams. We find that the parameter space saturating the $0νββ$ bounds remain allowed from the latest experimental bounds on charged lepton flavour violating decays like $μ\rightarrow e γ$. We finally include the bounds from cosmology and supernova to constrain the parameter space of the model.

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