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arXiv 1807.06987hep-ph
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复杂单重标量中自发的$CP$破坏电弱重子生成和暗物质

Spontaneous $CP$-Violating Electroweak Baryogenesis and Dark Matter from a Complex Singlet Scalar

Bohdan Grzadkowski, Da Huang

摘要:

CP非不变性是强烈限制目前的实验,而额外的CP破坏源需要一个成功的重子发生。受这些观测的启发,我们考虑了一个模型,该模型预测了宇宙在高温下CP的自发破坏和在目前温度下CP的恢复。此外,我们提出了一个暗物质(DM)的候选人,满足所有已知的属性DM。寻找一个满足上述条件的最小模型导致我们通过添加一个复杂的单重标量$S$来扩展基本相互作用的标准模型(SM)。我们将$CP$和$Z_2$对称性加在标量势上。当$S$的复真空期望值高于EW相变温度时,$CP$对称性自发破缺,容易实现强的一级电-弱相变.引入一个6维有效算符,给出了新的复杂的贡献的顶夸克质量,我们表明,它很容易产生所观察到的重子不对称性在我们的宇宙。另一方面,在EW相变后,$CP$和$Z_2$对称性得到恢复,从而满足了目前对$CP$破坏的强约束,$\Re S$或$\Im S$中较轻的一个可以成为暗物质的候选者.通过扫描参数空间,我们发现该模型可以同时解释暗物质遗迹丰度和重子不对称性,同时满足所有其他实验约束的区域。最后,我们讨论了标量势中的明确的$CP$对称性破缺,它可以动态地消除产生负重子不对称性的畴。发现这可以通过${\cal O}(10^{-15})$的微小显式$CP$违反相来实现。

英文摘要:

CP non-invariance is strongly limited by present experiments, while extra sources of CP-violation are needed for a successful baryogenesis. Motivated by those observations we consider a model which predicts spontaneous violation of CP at high temperature and restoration of CP at present temperature of the Universe. In addition we propose a dark matter (DM) candidate that meets all known properties of DM. Looking for a minimal model that satisfies the above conditions leads us to extending the Standard Model (SM) of fundamental interactions by adding a complex singlet scalar $S$. We impose the $CP$ and $Z_2$ symmetries on the scalar potential. With the complex vacuum expectation value of $S$ at the temperature higher than the EW phase transition, the $CP$ symmetry is spontaneously broken and a strong first-order electro-weak phase transition is easily realized. Introducing a dimension-6 effective operator that gives new complex contributions to the top quark mass, we show that it is easy to yield the observed baryon asymmetry in our Universe. On the other hand, the $CP$ and $Z_2$ symmetries are recovered after the EW phase transition so that the present strong constraints on $CP$ violation can be satisfied and the lighter of $\Re S$ or $\Im S$ can be the dark matter candidate. By scanning the parameter space, we find regions where the model can explain the dark matter relic abundance and the baryon asymmetry simultaneously while satisfying all other experimental constraints. Finally, we discuss the explicit $CP$ symmetry breaking in the scalar potential that can help dynamically eliminate the domains producing the negative baryon asymmetry. It is found that this can be achieved by a tiny explicit $CP$-violating phase of ${\cal O}(10^{-15})$.

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