D-brane disformal coupling and thermal dark matter
D-brane disformal coupling and thermal dark matter
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DOI：
10.1103/physrevd.96.103506
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发表时间：
2017-08
影响因子：
5
通讯作者：
B. Dutta;E. Jiménez;I. Zavala
中科院分区：
文献类型：
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作者：
B. Dutta;E. Jiménez;I. Zavala
标量场和物质之间的共形和非共形耦合在一般标量张量理论中自然发生。在宇宙学和粒子物理学的D-膜模型中，这些耦合源自描述横向（标量）和纵向（物质）涨落动力学的D-膜作用量，因此它们是耦合的。在后暴胀时期和大爆炸核合成（BBN）开始之前，这些耦合可以改变物质感受到的膨胀率，改变对暗物质粒子热遗迹丰度的预测，从而改变满足今天暗物质含量所需的湮灭率。我们研究了类D膜共形耦合和非形式耦合对BBN之前宇宙膨胀率的影响，以及它们对暗物质遗迹丰度和湮灭率的影响。对于纯粹的非形式耦合，膨胀率总是相对于标准的膨胀率提高。这就产生了更大的横截面相比，标准的热预测的范围内的暗物质质量，这将是探测未来的实验。在类似D膜的情况下，膨胀率增强发生的尺度取决于弦耦合和弦尺度。
Conformal and Disformal couplings between a scalar field and matter occur naturally in general scalar-tensor theories. In D-brane models of cosmology and particle physics, these couplings originate from the D-brane action describing the dynamics of its transverse (the scalar) and longitudinal (matter) fluctuations, which are thus coupled. During the post-inflationary regime and before the onset of big-bang nucleosynthesis (BBN), these couplings can modify the expansion rate felt by matter, changing the predictions for the thermal relic abundance of dark matter particles and thus the annihilation rate required to satisfy the dark matter content today. We study the D-brane-like conformal and disformal couplings effect on the expansion rate of the universe prior to BBN and its impact on the dark matter relic abundance and annihilation rate. For a purely disformal coupling, the expansion rate is always enhanced with respect to the standard one. This gives rise to larger cross-sections when compared to the standard thermal prediction for a range of dark matter masses, which will be probed by future experiments. In a D-brane-like scenario, the scale at which the expansion rate enhancement occurs depends on the string coupling and the string scale.