Relic Abundance in a Secluded Dark Matter Scenario with a Massive Mediator
Relic Abundance in a Secluded Dark Matter Scenario with a Massive Mediator
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DOI：
10.1103/physrevd.95.023006
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发表时间：
2016-07
影响因子：
5
通讯作者：
Shohei Okawa;M. Tanabashi;M. Yamanaka
中科院分区：
文献类型：
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作者：
Shohei Okawa;M. Tanabashi;M. Yamanaka
在一个隐蔽的暗物质场景中，研究了暗物质粒子d$的残余丰度，其中d$的数量减少过程主要不是通过d$对湮灭成为标准模型粒子，而是通过d$到mm$的散射过程，随后有一个衰变的中介粒子m$。指出，即使存在质量为m_m的大质量介质，与DM粒子质量m_d相比，质量为m_m的大质量介质，也可以实现宇宙学观测到的DM遗迹丰度。在简并的$d$-$m$情况下（$m_d=m_m$），通过调整$dd $到mm$的散射幅度和选择适当的介质粒子寿命来实现DM遗迹丰度。早期宇宙的DM演化表现出典型的“阶地”行为，即两步数密度递减行为，在第一步有一个“假”冻结。在此基础上，提出了一种新的DM模型建立的可能性，即介质粒子$m$与DM粒子$d$统一在近似暗对称多乘体中。在一个可重整的场论框架中，提出了一个子DM模型来说明这一思想。
The relic abundance of the dark matter (DM) particle $d$ is studied in a secluded DM scenario, in which the $d$ number decreasing process dominantly occurs not through the pair annihilation of $d$ into the standard model particles, but via the $dd \to mm$ scattering process with a subsequently decaying mediator particle $m$. It is pointed out that the cosmologically observed relic abundance of DM can be accomplished even with a massive mediator having a mass $m_m$ non-negligibly heavy compared with the DM particle mass $m_d$. In the degenerated $d$-$m$ case ($m_d=m_m$), the DM relic abundance is realized by adjusting the $dd \to mm$ scattering amplitude large enough and by choosing an appropriate mediator particle life-time. The DM evolution in the early universe exhibits characteristic "terrace" behavior, or two-step number density decreasing behavior, having a "fake" freeze-out at the first step. Based on these observations, a novel possibility of the DM model buildings is introduced in which the mediator particle $m$ is unified with the DM particle $d$ in an approximate dark symmetry multiplet. A pionic DM model is proposed to illustrate this idea in a renormalizable field theory framework.