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arXiv 2004.07705hep-ph
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来自半湮灭的非对称暗物质

Asymmetric dark matter from semi-annihilation

Avirup Ghosh, Deep Ghosh, Satyanarayan Mukhopadhyay

摘要:

我们表明,一般的半湮灭的情况下,一对暗物质(DM)粒子湮灭到反DM,和一个不稳定的状态,可以混合或衰变到标准模型状态,可以导致粒子反粒子不对称的DM部门。目前的DM丰度,包括CP违反DM部门和由此产生的目前的不对称性是完全由一个单一的半湮灭过程在下一个领先的顺序。对于大CP违反在这个过程中,我们发现,几乎完全的不对称性可以在DM部门,所观察到的DM密度占主导地位的(反)DM粒子。额外的对湮灭过程的存在下,可以修改DM和反DM数密度的比例进一步,如果对湮灭是活跃的半湮灭去耦之后。对于这样的场景,与仅存在半湮灭的场景相比,生成相同的当前不对称性所需的CP违反通常要小得多。我们发现,一个极小模型与一个复杂的标量DM与立方自相互作用可以引起半和对湮灭,所需的CP-违反在一个循环的水平。我们还发现,上界的DM质量从S-矩阵的幺正性在纯粹的不对称的半湮灭的情况下,最大CP违反,是15 GeV左右,这是强得多,比在WIMP和以前考虑的不对称DM的情况下,由于所需的大的非零化学势,这样的不对称DM。

英文摘要:

We show that a general semi-annihilation scenario, in which a pair of dark matter (DM) particles annihilate to an anti-DM, and an unstable state that can mix with or decay to standard model states, can lead to particle anti-particle asymmetry in the DM sector. The present DM abundance, including the CP-violation in the DM sector and the resulting present asymmetry are determined entirely by a single semi-annihilation process at next-to-leading order. For large CP-violation in this process, we find that a nearly complete asymmetry can be obtained in the DM sector, with the observed DM density being dominated by the (anti-)DM particle. The presence of additional pair-annihilation processes can modify the ratio of DM and anti-DM number densities further, if the pair-annihilation is active subsequent to the decoupling of the semi-annihilation. For such a scenario, the required CP-violation for generating the same present asymmetry is generically much smaller, as compared to the scenario with only semi-annihilation present. We show that a minimal model with a complex scalar DM with cubic self-interactions can give rise to both semi- and pair-annihilations, with the required CP-violation generated at one-loop level. We also find that the upper bound on the DM mass from S-matrix unitarity in the purely asymmetric semi-annihilation scenario, with maximal CP-violation, is around 15 GeV, which is much stronger than in the WIMP and previously considered asymmetric DM cases, due to the required large non-zero chemical potential for such asymmetric DM.

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