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arXiv 2602.17243hep-ph
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三共振轻子生成在非全纯模形式A4斯科廷模型中

Tri-Resonant Leptogenesis in a Non-Holomorphic Modular A$_4$ Scotogenic Model

Department of Physics and Astronomical Science, Central University of Himachal Pradesh(喜马偕尔中央大学物理与天文科学系)

Tapender, Surender Verma

AI总结:

该研究在非全纯模形式A4斯科廷模型中,通过三共振机制实现轻子生成,预测了中微子参数和重子生成的实验可检验性。

摘要:

我们研究了通过三共振轻子生成实现低能级重子生成,在包含标量暗物质的斯科廷模型中,采用非全纯模形式A4对称性框架。该模型自然容纳了当右 handed (RH) 中微子被分配到A4的三重表示时,三个几乎简并的RH中微子。近简并性源于将对称贡献到Majorana质量矩阵的对称部分,来自A4的3⊗3分解,视为主导单倍贡献的小扰动。模型中施加了广义CP (gCP) 对称性,使复模量τ成为唯一CP违反源。特别是对于倒置层次结构 (IH),预测的3σ范围的θ23位于下八象限接近最大值,而CP相位δCP和Majorana相位α21被预测接近0°或360°。此外,在这种情况下,预测的mee和∑i mi可以被未来的中微子less双β衰变(0νββ)实验以及宇宙学观测,特别是DESI+BAO和Planck数据所测试和限制。事实上,DESI+BAO否定了该模型中的IH。我们进一步表明,成功的重子生成可以在轻中微子质量的正常层次结构 (NH) 和倒置层次结构 (IH) 情况下实现,RH中微子质量低至537 GeV,使该场景具有实验可测试性。对于NH,RH中微子质量简并度为O(10^{-7}-10^{-6}),而对于IH则需要更强的简并度O(10^{-8})。值得注意的是,在NH情况下,即使在深洗出区域,衰变参数为O(10^5)时,成功的重子生成也可以发生,因为三共振增强了CP不对称性,并且考虑了味效应。

英文摘要:

We investigate low-scale baryogenesis \textit{via} tri-resonant leptogenesis within the scotogenic model with a scalar dark matter embedded in non-holomorphic modular $A_4$ symmetry framework. The model naturally accommodates three nearly degenerate right-handed (RH) neutrinos when they are assigned to the triplet representation of $A_4$. The near degeneracy originates from treating the symmetric contribution to the Majorana mass matrix, arising from the $\mathbf{3}\otimes\mathbf{3}$ decomposition of $A_4$, as a small perturbation to the dominant singlet contribution. Generalized CP (gCP) symmetry is imposed in the model, rendering the complex modulus $τ$ as the sole source of CP violation. In particular, for the inverted hierarchy (IH), the predicted $3σ$ range of $θ_{23}$ lies in the lower octant close to maximal value while CP phase $δ_{\mathrm{CP}}$ and the Majorana phase $α_{21}$ are predicted to lie close to $0^\circ$ or $360^\circ$. Also, in this case, predicted values of $m_{ee}$ and $\sum_i m_i$ can be tested and constrained by future neutrinoless double beta decay $(0νββ)$ experiments, as well as by cosmological observations, particularly DESI+BAO and Planck data. In fact DESI+BAO disallows IH in the model. We further show that successful baryogenesis can be achieved for both normal hierarchy (NH) and inverted hierarchy (IH) of light neutrino masses with RH neutrino masses as low as $537~\mathrm{GeV}$ rendering this scenario experimentally testable. For NH, RH neutrino mass degeneracy of $\mathcal{O}(10^{-7}\!-\!10^{-6})$ is required, while for IH a stronger degeneracy of $\mathcal{O}(10^{-8})$ is needed. Remarkably, in the NH case, successful baryogenesis can occur even in the deep washout regime with decay parameters of $\mathcal{O}(10^{5})$ owing to the tri-resonant enhancement of the CP asymmetry and the inclusion of flavor effects.

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