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arXiv 2310.09337hep-phhep-th
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带双重跷跷板机制的左右对称模型中的轻子生成

Leptogenesis in a Left-Right Symmetric Model with double seesaw

Utkarsh Patel, Pratik Adarsh, Sudhanwa Patra, Purushottam Sahu

AI总结:

本研究在带双重跷跷板的左右对称模型中,建立低标度CP破坏狄拉克相位与高标度轻子生成的关联,验证了该相位可独立产生所需轻子不对称性,并提出可通过振荡实验约束模型。

摘要:

我们在含标量双二重态与二重态的左右对称模型(LRSM)中,探究了低标度CP破坏狄拉克相位(δ)与高标度轻子生成之间的关联。该模型的费米子部分每代都引入了一个惰性中微子(S_L),以在中性费米子质量矩阵中实现双重跷跷板机制。双重跷跷板通过两次实施I型跷跷板机制实现:第一次跷跷板为重型右手中微子(N_R)生成马约拉纳质量项,第二次跷跷板则使轻中微子质量与S_L质量呈线性相关。在我们的框架中,选取电荷共轭(C)作为离散左右(LR)对称性,这一选择有助于根据轻、重型右手中微子质量以及包含δ的轻中微子混合矩阵U_PMNS推导狄拉克中微子质量矩阵(M_D)。我们以右手中微子质量为输入参数,利用得到的M_D验证了通过右手中微子衰变实现的无味热轻子生成的可行性。我们在无味区域对描述不对称性演化的玻尔兹曼方程进行了完整分析,结果表明,在给定输入参数选择下,无论是否存在马约拉纳相位,CP破坏狄拉克相位都足以在该框架内的轻子部分产生所需的不对称性。最后,我们讨论了利用当前及近期旨在精确测定δ值的振荡实验来约束本模型的可能性。

英文摘要:

We explore the connection between low-scale CP-violating Dirac phase~$(δ)$ and high-scale leptogenesis in a Left-Right Symmetric Model (LRSM) with scalar bidoublet and doublets. The fermion sector of the model is extended with one sterile neutrino~$(S_L)$ per generation to implement a double seesaw mechanism in the neutral fermion mass matrix. The double seesaw is performed via the implementation of type-I seesaw twice. The first seesaw facilitates the generation of Majorana mass term for heavy right-handed (RH) neutrinos~$(N_R)$, and the light neutrino mass becomes linearly dependent on $S_L$ mass in the second. In our framework, we have taken charge conjugation ($C$) as the discrete left-right (LR) symmetry. This choice assists in deriving the Dirac neutrino mass matrix ($M_D$) in terms of the light and heavy RH neutrino masses and light neutrino mixing matrix $U_{PMNS}$ (containing $δ$). We illustrate the viability of unflavored thermal leptogenesis via the decay of RH neutrinos by using the obtained $M_D$ with the masses of RH neutrinos as input parameters. A complete analysis of the Boltzmann equations describing the asymmetry evolution is performed in the unflavored regime, and it is shown that with or without Majorana phases, the CP-violating Dirac phase is sufficient to produce the required asymmetry in the leptonic sector within this framework for a given choice of input parameters. Finally, we comment on the possibility of constraining our model with the current and near-future oscillation experiments, which are aimed at refining the value of $δ$.

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