标题： 规范化的$L_e-L_μ-L_τ$对称性，第四代，中微子质量和暗物质 显示英文标题

标题： Gauged $L_e-L_μ-L_τ$ symmetry, fourth generation, neutrino mass and dark matter

摘要： 我们提出了两种模型，在其中熟悉的轻子对称性$L_e-L_\mu-L_\tau$是规范对称性。 我们展示了如何通过反常消除来限制允许的理论，其中一个需要第四代顺序手征标准模型费米子族，而另一个具有三代时，需要将$(L_e-L_\mu-L_\tau)-(B_1-B_2-B_3)$与代表第$a$代夸克的重子数$B_a$进行规范。 与总是导致中微子倒序质量层次的全局$L_e-L_\mu-L_\tau$模型不同，规范版本可以导致正常质量层次。 我们展示了如何在两种情况下构建现实的模型，并讨论了两者中的暗物质候选者。 在我们的模型中，$U(1)_{L_e-L_\mu-L_\tau}$的破缺通过 I 型机制负责产生中微子质量，而$U(1)_{L_e-L_\mu-L_\tau}$的破缺标量场的实部（这里称为$\phi$）充当冻干暗物质候选者。 由于$\phi$是不稳定的，为了使其成为暗物质，其寿命必须大于宇宙的年龄，这意味着$\phi$的遗迹是通过冻干机制产生的，且其质量必须小于 1 MeV。 我们还讨论了同时解释 μ 子和电子$(g-2)$的可能性，同时满足暗物质遗迹密度和寿命限制的一致性。 显示英文摘要

摘要： We present two models where the familiar leptonic symmetry $L_e-L_\mu-L_\tau$ is a gauge symmetry. We show how anomaly cancellation constrains the allowed theories, with one of them requiring a fourth sequential chiral standard model fermion generation and a second one with three generations, requiring gauging of $(L_e-L_\mu-L_\tau)-(B_1-B_2-B_3)$ with $B_a$ representing the baryon number of the $a$th generation quarks. Unlike global $L_e-L_\mu-L_\tau$ models which always leads to inverted mass hierarchy for neutrinos, the gauged version can lead to normal hierarchy. We show how to construct realistic models in both the cases and discuss the dark matter candidate in both. In our model, the breaking of $U(1)_{L_e-L_\mu-L_\tau}$ is responsible for neutrino mass via type-I mechanism whereas the real part of $U(1)_{L_e-L_\mu-L_\tau}$ breaking scalar field (called $\phi$ here) plays the role of freeze-in dark matter candidate. Since $\phi$ is unstable, for it to qualify as dark matter, its lifetime must be larger than the age of the Universe, implying that the relic of $\phi$ is generated through freeze-in mechanism and its mass must be less than an MeV. We also discuss the possibility of explaining both muon and electron $(g-2)$ while being consistent with the dark matter relic density and lifetime constraints.