arXiv 1808.033522018-08-09hep-ph

新B-L模型中的双组分暗物质和无质量中微子

Two-component dark matter and a massless neutrino in a new B-L model

Nicolas Bernal, Diego Restrepo, Carlos Yaguna, Oscar Zapata

备注：: 23 pages
发表信息：: Phys. Rev. D 99, 015038 (2019)
DOI：: 10.1103/PhysRevD.99.015038

摘要：

我们提出了一个新的标准模型的$U(1)_{B-L}$规范对称性的扩展，其中的异常被取消的两个右手中微子和四个手征费米子分数B-L电荷。还需要两个标量场来打破B-L对称性，并给新的费米子以质量。对称破缺后，两个中微子通过跷跷板机制获得马约拉纳质量，在光谱中留下一个无质量的中微子。此外，其他新的费米子将自己排列成两个狄拉克粒子，这两个粒子都是自动稳定的，并有助于观察到的暗物质密度。因此，这个模型实现了一个自然的方式，没有特设离散对称性，一个两个组件的暗物质的情况。我们详细分析了这个模型的暗物质现象。说明了模型参数对遗迹密度的依赖关系，并确定了与观测到的暗物质丰度一致的区域。最后，我们施加了大型强子对撞机和直接探测实验的电流限制，并表明该模型的高质量区域仍然不受约束。

英文摘要：

We propose a new extension of the Standard Model by a $U(1)_{B-L}$ gauge symmetry in which the anomalies are canceled by two right-handed neutrinos plus four chiral fermions with fractional B-L charges. Two scalar fields that break the B-L symmetry and give masses to the new fermions are also required. After symmetry breaking, two neutrinos acquire Majorana masses via the seesaw mechanism leaving a massless neutrino in the spectrum. Additionally, the other new fermions arrange themselves into two Dirac particles, both of which are automatically stable and contribute to the observed dark matter density. This model thus realizes in a natural way, without ad hoc discrete symmetries, a two-component dark matter scenario. We analyze in some detail the dark matter phenomenology of this model. The dependence of the relic densities with the parameters of the model is illustrated and the regions consistent with the observed dark matter abundance are identified. Finally, we impose the current limits from LHC and direct detection experiments, and show that the high mass region of this model remains unconstrained.

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