[论文解读] Early inflation induced gravity waves can restrict Astro-Particle physics

S. Nussinov|arXiv (Cornell University)|Aug 6, 2014

Cosmology and Gravitation Theories参考文献 1被引用 5

一句话总结

本文研究了高尺度暴胀和高再加热温度对天体粒子物理的约束，特别是对冷暗物质（CDM）模型的约束。研究发现，若不引入晚期熵注入或新相互作用，质量大于20 GeV的重暗物质粒子（X）通过标准冻结-out过程将过度产生，违反CDM遗迹密度限制。其主要贡献在于证明，仅当存在规范性非阿贝尔规范相互作用且尺度Λ′ < M(X)时，才能通过形成束缚态和通量管实现高效的晚期湮灭，从而缓解这一矛盾。

ABSTRACT

In this paper, we discuss limits on various astro-particle scenarios if the scale extit{and} the reheat temperature of the last relevant inflation were very high. While the observed "B" like pattern of polarizations of the CMB suggest a very high ($\ge 10^{16}\ GeV$) scale of a primordial (which motivated this work initially) and may reflect effects of dust, we believe that addressing these issues is nonetheless very useful. We recall the potential difficulties with various topological defects - monopoles, strings and domain walls generated at the SSB (spontaneous symmetry breaking) of various gauge symmetries. The main part of the paper is devoted to discussing difficulties with long-lived heavy particles, which could be dark matter but cannot efficiently annihilate to the required residual density because of basic S-Matrix unitarity/analyticity limits. We indicate in simple terms yet in some detail how the WIMP miracle occurs at $M(X)\sim{TeV}$ and how the axiomatic upper bound presently updated to $M(X) \le{110 TeV}$ was originally derived by Greist and Kamionokowski. We also argue that generically we expect the stronger $M(X)\le{20\ GeV}$ bound to hold. We then elaborate on the pure particle physics approaches aiming to enhance the annihilation and evade the bounds. We find that the only and in fact very satisfactory way of doing this requires endowing the particles with gauge interactions with a confinement scale lower than $M(X)$. We also comment on models with light $O(KeV)$ dark matter, which was supposed to be frozen in via out-of equilibrium processes so as to have the right relic densities pointing out that in many such cases extit{very} low reheat temperatures are indeed required and speculate on the large desert scenario of particle physics. Most of what we discuss is not new but was not presented in a coherent fashion.

研究动机与目标

• 在高尺度暴胀和高再加热温度的假设下，考察对天体粒子物理模型的约束。
• 识别为何标准重暗物质候选者（如WIMPs）在质量>20 GeV时，除非增强湮灭，否则将过度产生。
• 探索规避湮灭截面S矩阵幺正性限制的机制。
• 评估以keV量级为特征的暗物质候选者在非平衡状态下通过冻结生成的可行性。
• 评估在电弱尺度与普朗克/大统一理论尺度之间存在巨大物理空白的假设是否与宇宙学约束一致。

提出的方法

• 利用S矩阵幺正性和解析性边界对湮灭振幅进行分析，研究热冻结-out过程中的遗迹密度约束。
• 应用Greist-Kamionokowski（GK）边界对湮灭截面进行分析，推导出暗物质质量的上限（M(X) ≤ 110 GeV），并提出更强的边界M(X) ≤ 20 GeV。
• 考虑规范性非阿贝尔规范相互作用在Λ′ < M(X)条件下的作用，通过束缚态和通量管的形成增强湮灭速率。
• 评估以keV量级为特征、在非平衡状态下生成的暗物质模型，避免在低再加热温度下导致过度闭合。
• 评估晚期熵注入（如模场衰变或其他长寿命粒子衰变）作为稀释机制的影响。
• 比较S矩阵框架在描述规范性时的失效，从而论证解决过度产生问题需依赖非微扰动力学。

实验结果

研究问题

• RQ1 若暴胀后的再加热温度较高，对质量M(X) > 20 GeV的重暗物质候选者存在何种宇宙学约束？
• RQ2 S矩阵振幅的幺正性和解析性边界如何限制长寿命重粒子的湮灭截面？
• RQ3 为何原始的Greist-Kamionokowski边界M(X) ≤ 340 TeV过弱？更仔细的分析为何能导出更紧的上限？
• RQ4 规范性非阿贝尔规范相互作用（Λ′ < M(X)）是否能解决重暗物质的过度产生问题？
• RQ5 在高再加热温度宇宙学模型下，keV量级暗物质模型是否可行？需要多低的再加热温度才能避免过度闭合？

主要发现

• 标准S矩阵幺正性和解析性边界表明，若不增强湮灭截面，质量M(X) > 20 GeV的暗物质粒子无法通过热冻结-out实现正确的遗迹密度。
• 原始的Greist-Kamionokowski边界M(X) ≤ 340 TeV已被更紧的上限M(X) ≤ 110 GeV所取代，且论证认为M(X) ≤ 20 GeV在一般情况下是成立的。
• 仅当规范性非阿贝尔规范相互作用的尺度Λ′显著低于M(X)时，才能显著增强湮灭速率，实现高效的晚期湮灭，从而解决过度产生问题。
• 以keV量级为特征、在非平衡状态下生成的暗物质模型仅在再加热温度足够低以避免热过度产生时才可行。
• 若无晚期熵注入或新相互作用，则高再加热温度宇宙学强烈限制可行的暗物质模型。
• 大空白场景（即电弱尺度与普朗克/GUT尺度之间缺乏新物理）依然合理，因为高尺度暴胀和再加热并未排除这一间隙的存在。