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arXiv 2206.13530hep-phastro-ph.CO
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暗辐射对与隐藏扇区门户相互作用的约束

Dark radiation constraints on portal interactions with hidden sectors

Peter Adshead, Pranjal Ralegankar, Jessie Shelton

AI总结:

本文更新了暗辐射对标准模型中毫电荷粒子和$B-L$规范扩展的约束,通过引入量子统计与非平衡效应改进了$B-L$模型分析,并推导出通用隐藏扇区辐射密度的下限。

摘要:

我们更新了暗辐射对毫电荷粒子(MCP)和规范重子数减去轻子数($B-L$)的标准模型(SM)扩展的约束。在这些模型中,一个有质量的SM规范单态媒介子将SM等离子体与额外的SM单态轻度自由度耦合起来。在早期宇宙中,这些新的轻粒子通过SM与MCP或新的$B-L$规范玻色子的相互作用产生,并作为暗辐射。早期宇宙中暗辐射的存在受到当前和即将进行的宇宙微波背景(CMB)测量的严格约束。我们根据当前$N_{\ m eff}$的测量结果更新了对MCP的界限,并表明未来的CMB实验将能够排除或发现为解释EDGES异常而引入的扩展MCP模型。我们对规范$B-L$模型的分析超越了以往的研究,包含了量子统计和非平衡效应。此外,我们考虑了$B-L$规范玻色子的有限寿命,这会提升随后的右手中微子能量密度。我们还开发了一些近似和方法,用于简化和求解相关的玻尔兹曼方程。我们利用这些近似推导出了具有轻遗迹的通用隐藏扇区中辐射密度的下限,该下限不依赖于隐藏扇区的具体细节,前提是媒介子与隐藏扇区的相互作用比与SM的相互作用更强。

英文摘要:

We update dark radiation constraints on millicharged particle (MCP) and gauged baryon-number-minus-lepton-number ($B-L$) extensions of the Standard Model (SM). In these models, a massive SM gauge singlet mediator couples the SM plasma to additional SM-singlet light degrees of freedom. In the early Universe, these new light particles are populated via the interaction of the SM with the MCP, or the new $B-L$ gauge boson, and act as dark radiation. The presence of dark radiation in the early Universe is tightly constrained by current and upcoming cosmic microwave background (CMB) measurements. We update bounds on MCPs from current measurements of $N_{\rm eff}$ and show that future CMB experiments will be able to rule out or discover the extended MCP model invoked to explain the EDGES anomaly. Our analysis of the gauged $B-L$ model goes beyond previous studies by including quantum-statistical and out-of-equilibrium effects. Further, we account for the finite lifetime of the $B-L$ gauge boson, which boosts the subsequent right-handed neutrino energy density. We also develop a number of approximations and techniques for simplifying and solving the relevant Boltzmann equations. We use our approximations to develop a lower bound on the radiation density in a generic hidden sector with a light relic that is insensitive to the details of the hidden sector, provided the mediator interacts more strongly with the hidden sector than with the SM.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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