[论文解读] Stochastic Finsler D-particle Space-Time Foam Enhances Dark Matter Relics

Nick E. Mavromatos, V. A. Mitsou+2 more|arXiv (Cornell University)|Dec 18, 2010

Cosmology and Gravitation Theories被引用 1

一句话总结

本文提出了一种在弦/膜理论中基于随机Finsler D-膜泡沫的模型，该模型诱导出动力学的、非黎曼几何的时空结构，导致轻希格斯粒子暗物质（LSP）热余晖丰度增强。该模型表明，D-膜反冲产生随机Finsler度量，该度量作为玻尔兹曼方程中的源项，使TeV量级D-膜质量下的LSP余晖密度超出ΛCDM预测，对对撞机和伽马射线天文学约束具有重要意义。

ABSTRACT

Within the context of supersymmetric space-time (D-particle) foam in string/brane-theory, we discuss a Finsler-induced Cosmology and its implications for (thermal) Dark Matter abundances. This constitutes a truly microscopic model of dynamical space-time, where Finsler geometries arise naturally. The D-particle foam model involves point-like brane defects (D-particles), which provide the topologically non-trivial foamy structures of space-time. The D-particles can capture and emit stringy matter and this leads to a recoil of D-particles. It is indicated how one effect of such a recoil of D-particles is a back-reaction on the space-time metric of Finsler type which is stochastic. We show that such a type of stochastic space-time foam can lead to acceptable cosmologies at late epochs of the Universe, due to the non-trivial properties of the supersymmetric (BPS like) D-particle defects, which are such so as not to affect significantly the Hubble expansion. The restrictions placed on the free parameters of the Finsler type metric are obtained from solving the Boltzmann equation in this background for relic abundances of a Lightest Supersymmetric Particle (LSP) dark matter candidate. It is demonstrated that the D-foam acts as a source for particle production in the Boltzmann equation, thereby leading to enhanced thermal LSP relic abundances relative to those in the Standard LambdaCDM Cosmology. For D-particle masses of order TeV, such effects may be relevant for dark matter searches at colliders. The latter constraints complement those coming from high energy gamma-ray astronomy on the induced vacuum refractive index that D-foam models entail. We also comment briefly on the production mechanisms of such TeV-mass stringy defects at colliders, which, in view of the current LHC experimental searches, will impose further constraints on their couplings.

研究动机与目标

• 开发基于弦/膜理论中D-膜的时空泡沫微观动力学模型。
• 研究由D-膜反冲引起的Finsler几何如何修改宇宙学演化及暗物质余晖丰度。
• 确定此类随机Finsler背景是否能在不破坏哈勃膨胀的前提下维持与晚期宇宙学的一致性。
• 量化由于D-泡沫诱导的粒子产生在玻尔兹曼方程中对热LSP余晖丰度的增强效应。
• 评估在对撞机和高能伽马射线观测约束下，TeV量级D-膜的理论可行性。

提出的方法

• 将时空泡沫建模为捕捉并发射弦物质的BPS类D-膜缺陷网络，从而引发反冲。
• 推导出作为D-膜反冲后反应的随机Finsler型度量，引入非平凡的、非黎曼几何结构。
• 在该随机Finsler背景下求解LSP余晖丰度的玻尔兹曼方程，将D-泡沫视为粒子产生的源项。
• 通过要求与观测到的晚期宇宙学和哈勃膨胀一致，对Finsler度量的自由参数施加约束。
• 将预测的余晖丰度与标准ΛCDM模型进行比较，以量化增强效应。
• 评估对撞机和伽马射线天文观测对真空折射率及D-膜耦合的约束。

实验结果

研究问题

• RQ1 在超对称D-膜泡沫模型中，随机Finsler几何如何从D-膜反冲中涌现？
• RQ2 Finsler诱导的时空泡沫在多大程度上增强了轻希格斯粒子（LSP）的热余晖丰度？
• RQ3 此类模型能否与晚期宇宙学观测保持一致，特别是哈勃膨胀速率？
• RQ4 对撞机搜索和高能伽马射线天文学对TeV量级D-膜施加了哪些现象学约束？
• RQ5 玻尔兹曼方程中D-泡沫诱导的粒子产生项如何修改标准暗物质余晖密度计算？

主要发现

• 由D-膜反冲产生的随机Finsler度量导致时空几何的非平凡修正，同时保持与晚期宇宙学的一致性。
• D-泡沫在玻尔兹曼方程中充当源项，导致LSP热余晖丰度显著高于标准ΛCDM预测。
• 对于TeV量级的D-膜质量，余晖丰度的增强效应变得显著，并可能在未来对撞机实验中被探测到。
• 该模型通过与观测到的哈勃膨胀和晚期宇宙学的一致性，对Finsler度量的自由参数施加了约束。
• 高能伽马射线天文学对真空折射率的约束为D-泡沫模型提供了补充限制。
• 当前LHC对弦状缺陷的搜索进一步约束了TeV量级D-膜的耦合，限制了其现象学可行性。