arXiv 1809.035192018-09-10hep-phastro-ph.CO

快速膨胀宇宙中的keV中微子暗物质

keV Neutrino Dark Matter in a Fast Expanding Universe

Anirban Biswas, Debasish Borah, Dibyendu Nanda

备注：: 23 pages, 5 figures
发表信息：: Phys. Lett. B786, 364 (2018)
DOI：: 10.1016/j.physletb.2018.10.012

摘要：

本文研究了标准模型的最小$U(1)_{B-L}$规范扩展中存在keV中微子暗物质的可能性。在不考虑额外的粒子或对称性的情况下，我们认为最轻的右手中微子在keV质量范围内，这是运动学上长寿命的。由于规范相互作用，这样的keV中微子可以在早期宇宙中热产生，然后在相对论性的情况下去耦。这种keV中微子的最终剩余丰度通常会超过宇宙，需要额外的机制将其置于观测极限之下。我们提出了一个非标准的宇宙学历史的标量场$ϕ$，红移速度比辐射占主导地位的宇宙之前，辐射占主导地位的时代。我们发现，这样一个非标准的阶段可以保持丰富的热生成keV中微子暗物质内观察到的遗迹丰度。我们约束的非标准相，$U(1)_{B-L}$参数从这些要求，也简要地评论后，观测方面的keV中微子暗物质。

英文摘要：

We study the possibility of keV neutrino dark matter in the minimal $U(1)_{B-L}$ gauge extension of the standard model where three right handed neutrinos are automatically included due to the requirement of anomaly cancellations. Without considering extra additional particles or symmetries, we consider the lightest right handed neutrino to be in the keV mass range which is kinematically long lived. Due to gauge interactions, such a keV neutrino can be thermally produced in the early Universe followed by decoupling while being relativistic. The final relic abundance of such keV neutrino typically overclose the Universe requiring additional mechanism to bring it under observed limits. We propose a non-standard cosmological history where a scalar field $ϕ$, that redshifts faster than radiation dominates the Universe prior to the radiation dominated era. We show that such a non-standard phase can keep the abundance of thermally generated keV neutrino dark matter within observed relic abundance. We constrain the non-standard phase, $U(1)_{B-L}$ parameters from these requirements and also briefly comment upon the observational aspects of such keV neutrino dark matter.

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