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arXiv 1612.03067hep-ph
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U $(1)_{L_μ-L_τ}$模型中的FIMP和μ子($g-2$)

FIMP and Muon ($g-2$) in a U$(1)_{L_μ-L_τ}$ Model

Anirban Biswas, Sandhya Choubey, Sarif Khan

摘要:

对标准热WIMP场景的限制越来越严格,迫使物理学家提出替代的暗物质(DM)模型。DM起源的最流行的替代解释之一是通过冷冻的DM的非热生产。在这种情况下,由于DM与热浴中的其他颗粒的弱耦合强度($\sim 10^{-12}$),DM永远不会与热汤达到热平衡,并且通常被称为弱相互作用块状颗粒(FIMP)。在这项工作中,我们提出了一个规范U(1)$_{L_μ-L_τ}$扩展的标准模型(SM),它有一个标量的FIMPDM候选人,并能一致地解释DM遗迹密度界。此外,U(1)$_{L_μ-L_τ}$规范对称性的自发破缺产生了额外质量的中性规范玻色子$Z_{μτ}$,它可以通过对过程的额外单圈贡献来解释μ子($g-2$)数据。最后,三个右手中微子的存在使得模型能够通过I型跷跷板机制成功地解释小中微子质量。自发破缺的U(1)$_{L_μ-L_τ}$的存在给出了轻中微子质量矩阵的一种特殊结构,这种结构可以解释轻中微子的特殊混合模式。

英文摘要:

The tightening of the constraints on the standard thermal WIMP scenario has forced physicists to propose alternative dark matter (DM) models. One of the most popular alternate explanations of the origin of DM is the non-thermal production of DM via freeze-in. In this scenario the DM never attains thermal equilibrium with the thermal soup because of its feeble coupling strength ($\sim 10^{-12}$) with the other particles in the thermal bath and is generally called the Feebly Interacting Massive Particle (FIMP). In this work, we present a gauged U(1)$_{L_μ-L_τ}$ extension of the Standard Model (SM) which has a scalar FIMP DM candidate and can consistently explain the DM relic density bound. In addition, the spontaneous breaking of the U(1)$_{L_μ-L_τ}$ gauge symmetry gives an extra massive neutral gauge boson $Z_{μτ}$ which can explain the muon ($g-2$) data through its additional one-loop contribution to the process. Lastly, presence of three right-handed neutrinos enable the model to successfully explain the small neutrino masses via the Type-I seesaw mechanism. The presence of the spontaneously broken U(1)$_{L_μ-L_τ}$ gives a particular structure to the light neutrino mass matrix which can explain the peculiar mixing pattern of the light neutrinos.

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