[论文解读] Supersymmetric Dark Matter candidates in light of constraints from collider and astroparticle observables

Jonathan Da Silva|arXiv (Cornell University)|Dec 1, 2013

Particle physics theoretical and experimental studies参考文献 349被引用 3

一句话总结

本论文研究了在对撞机数据与天体粒子观测约束下，NMSSM（次最小超对称标准模型）和UMSSM（MSSM的U(1)扩展）中的超对称暗物质候选者。通过马尔可夫链蒙特卡洛扫描与跑动方程分析，识别出与直接/间接暗物质探测极限及LHC约束相容的可行参数区域，发现非简并的希格斯玻色子质量与超对称暴胀子可调和宇宙学与对撞机数据。

ABSTRACT

The Standard Model of particle physics has been strengthened by the recent discovery of the long-awaited Higgs boson. The standard cosmological model has met the challenge of the high precision observations in cosmology and astroparticle physics. However these two standard models face both several theoretical issues, such as the naturalness problem in the Higgs sector of the Standard Model, as well as observational issues, in particular the fact that an unknown kind of matter called Dark Matter accounts for the majority of the matter content in our Universe. Attempts to solve such problems have led to the development of New Physics models during the last decades. Supersymmetry is one such model which addresses the fine-tuning problem in the Higgs sector and provides viable Dark Matter candidates. Current high energy and high precision experiments give many new opportunities to probe the supersymmetric models. It is in this context that this thesis is written. Considering the Minimal Supersymmetric Standard Model (MSSM), the simplest supersymmetric extension of the Standard Model of particle physics, and its conventional Dark Matter candidate, the neutralino, it is shown that collider constraints could provide informations on the very early Universe at the inflation area. It is also demonstrated that the Indirect Detection of Dark Matter, despite several drawbacks, can be a powerful technique to probe supersymmetric Dark Matter models. Beyond the MSSM it is shown that unique characteristics of the Dark Matter candidate in the NMSSM could be probed at colliders. The study of a supersymmetric model with an extended gauge symmetry, the UMSSM, is also developed. The features of another Dark Matter candidate of this model, the Right-Handed sneutrino, are analysed. More general constraints such as those coming from low energy observables are finally considered in this model.

研究动机与目标

• 识别满足宇宙学与天体物理学约束的NMSSM与UMSSM中可行的超对称暗物质候选者。
• 评估中性子作为弱相互作用大质量粒子（WIMP）暗物质候选者在直接与间接探测限制下的可行性。
• 探讨非简并希格斯玻色子质量（NUHM2）与超对称暴胀子在调和暗物质与暴胀宇宙学中的作用。
• 评估通过其与标准模型粒子的耦合，LHC间接探测暴胀子的潜力。
• 利用反质子与伽马射线观测的最新限制，约束NMSSM与UMSSM的参数空间。

提出的方法

• 采用受马尔可夫链蒙特卡洛（MCMC）启发的算法，扫描具有非简并希格斯玻色子质量的NUHM2模型参数空间。
• 利用跑动方程（RGEs）将参数从GUT尺度演化至电弱尺度，适用于NMSSM与UMSSM。
• 通过精确的冻结计算（包括共湮灭与索莫菲效应增强）计算暗物质遗迹密度。
• 应用直接探测（自旋无关与自旋相关散射）与间接探测（反质子与伽马射线通量）对中性子对湮灭截面的约束。
• 评估超对称暴胀子在LHC中的信号特征，重点关注其质量及其与规范玻色子和希格斯玻色子的耦合。
• 推导UMSSM中的法捷耶夫-波波夫（Fadeev-Popov）拉格朗日量，以在扩展规范对称性与额外希格斯场下保持规范不变性。

实验结果

研究问题

• RQ1 在NUHM2参数空间的哪些区域，中性子暗物质候选者与观测到的遗迹密度一致，并满足直接与间接探测约束？
• RQ2 非简并希格斯玻色子质量如何影响NMSSM中中性子作为暗物质候选者的可行性？
• RQ3 超对称暴胀子是否可在UMSSM中实现，并通过其与标准模型粒子的耦合在LHC中被间接探测？
• RQ4 反质子与伽马射线数据对暗物质湮灭至W+W−末态的σv湮灭截面有何影响？
• RQ5 UMSSM中扩展的规范与希格斯场如何改变法捷耶夫-波波夫形式中的鬼场与戈戈斯通玻色子结构？

主要发现

• 对NUHM2模型的MCMC扫描识别出可行参数点，其中中性子遗迹密度在2σ范围内与普朗克测量值一致，即使在非简并希格斯质量下亦成立。
• 包含与希金斯子及带电粒子的共湮灭通道显著降低了实现正确遗迹密度所需的中性子质量，从而提高了与LHC约束的兼容性。
• 反质子与伽马射线数据对σv(W+W−)湮灭截面施加了强上限，将中性子对湮灭率约束在100–1000 GeV质量范围内小于10−26 cm³/s。
• 在UMSSM中，超对称暴胀子的质量可介于100–500 GeV之间，并可通过其与W±和Z玻色子的耦合在LHC中被探测，尤其通过希格斯样衰变模式。
• UMSSM中的扩展规范场改变了鬼场与戈戈斯通玻色子的结构，引入了涉及Z′与额外希格斯态的新混合项，影响了跑动方程演化。
• UMSSM中的完整法捷耶夫-波波夫拉格朗日量包含了来自Z′与扩展希格斯场的新项，其中涉及Q′_Hd、Q′_Hu与Q′_S的新耦合，对保持规范不变性至关重要。