超对称标量中微子暗物质的唯象学研究

Naturalness problem and absence of dark matter in Standard Model are the basic motivations to look for new physics. Due to its elegance and consistency, low energy supersymmetry becomes well studied in literature. However most parameter space of Neutralino dark matter in MSSM is ruled out by the requirement of relic density as well as the null result of direct detection. Motivated by these arguments in this document we investigate the physics of a very slight modification of the usual SUSY LSP hypothesis that naturally and simply accommodates a much more structured and varied DM sector. Specifically we study what we consider to be one of the simplest alternatives to standard SUSY Neutralino DM, though maintaining the SUSY framework that naturally possesses the well-known successes of weak-scale SUSY theories, namely Sneutrino DM. The dedicated models are divided into two categories: One is the direct combination of MSSM and right handed neutrino superfield. We focus on the computation of sommerfeld enhancement induced by scalar higgs and its impact on relic density. The other is Sneutrino sector in U(1) extended BLSSM model in which we study the self-interacting cross section and the important constraints from BBN and CMB. Then we can systematically study the potential signal in direct and indirect detections. This project has deep implications on the on-going direct and indirect detection experiments in our country.

标准模型的自然性和暗物质问题是促使我们寻找新物理的主要动机。由于理论本身的优美和自洽，低能超对称作为新物理模型的候选者之一得到了广泛的关注。然而在最小的超对称模型（MSSM）中，通常的暗物质候选者Neutralino其大部分参数空间被残余密度，直接探测的限制排除。基于以上情况，本项目中我们在保证超对称自然性的前提下研究常规超对称暗物质的变种－Sneutrino的唯象学。具体的模型分为两类：一类在MSSM中直接加入右手中微子的Sneutrino，研究交换标量希格斯粒子引起的索末菲增强以及其对暗物质残余密度的影响；另一类是在U(1) 扩展的BLSSM中的Sneutrino，计算自相互作用散射截面以及对应的BBN，CMB限制。基于以上计算深入分析两类模型在直接探测，间接探测上的可能信号。该项目对我国正在进行的暗物质直接，间接探测实验都有着重要的理论价值

暗物质物理学中最重要和最前沿的方向之一是研究超对称和非超对称模型中的长程力效应。在计算暗物质遗迹密度和间接探测信号时，索末菲增强和辐射束缚态的形成至关重要。Singlino、sneutrino和其他超对称或非超对称暗物质候选者可以有效的提供长程力，包括非对角线势的存在。长程力模型有着丰富的现象学和强大的预测能力。..本项目主要研究暗物质的长程力影响及其与宇宙学演化、轻暗物质直接探测方案和精密测量实验的关系。(1)我们提出了一种不引入轻媒介粒子的u-channel共振的索末菲增强的新机制。(2) 我们提出了两种不同的暗物质模型来解释Xenon1T观测到的电子反冲信号。前者是通过宇宙线和大气散射产生的高能暗物质和电子发生弹性碰撞。后者则是通过暗物质非弹性碰撞中转移的能量来解释能谱的峰结构。(3) 通过精确计算辐射束缚态形成的截面，我们推导出希格斯媒介子暗物质中的遗迹密度和CMB电离效应。 (4) 暗物质也与长期存在的异常现象，即缪子反常磁矩有关。 我们提出了sgoldstino和特定味道的标量媒介粒子方案来解释这个反常现象。(5) 我们构造了B-L推广的超对称模型。其中详细讨论了Sneutrino，Blino和Bileptino暗物质的可行性。理论界和实验界的同仁们都对这些工作给予了密切关注和高度评价。这对于确定暗物质的存在和长程力效应至关重要。