超对称模型中的膨胀子优势弛豫LHC和宇宙学约束
Dilaton dominance relaxes LHC and cosmological constraints in supersymmetric models
摘要：
最近有人指出，如果宇宙在暗物质退耦时不是辐射主导的，那么早期宇宙中的介子场的存在会稀释中性伴子暗物质（DM）的丰度，这是由于它与DM的类耗散耦合。在这种情况下，两种基本机制相互竞争，修正后的哈勃膨胀率倾向于增加遗迹密度，而耗散力则倾向于降低遗迹密度，净效应可能导致预测的遗迹丰度总体上急剧下降，有时下降的数量级为O（10 ^2）左右。这个特征是相当普遍的，独立于对弦动力学的任何特定假设，假设在暴胀结束后但在大爆炸核合成（BBN）之前的早期时期，强子占主导地位。后者确保BBN不会因膨胀子的存在而被扰乱。在本文中，在这样一个场景的背景下，我们研究的约束最小超对称模型（CMSSM）的现象，考虑到所有最近的实验约束，包括那些从LHC搜索。我们发现，允许的参数空间大大扩大，包括区域超出了大型强子对撞机的范围。允许的区域是兼容的直接暗物质的搜索，因为小的中性伴子湮灭率，这是符合宇宙学数据的遗迹密度，意味着小的中性伴子核子截面低于直接暗物质实验的灵敏度。同样重要的是，新的宇宙学接受的区域与质量大于120 GeV的希格斯玻色子相容，正如LHC实验数据所表明的那样。较小的湮灭截面需要解释WMAP数据要求探测器性能的当前和计划通过伽马射线的间接DM搜索实验，应大大提高，以探测CMSSM地区。
英文摘要：
It has been pointed out recently that the presence of dilaton field in the early Universe can dilute the neutralino dark matter (DM) abundance, if Universe is not radiation dominated at DM decoupling, due to its dissipative-like coupling to DM. In this scenario two basic mechanisms compete, the modified Hubble expansion rate tending to increase the relic density and a dissipative force that tends to decrease it. The net effect can lead to an overall dramatic decrease of the predicted relic abundance, sometimes by amounts of the order of O(10^2) or so. This feature is rather generic, independent of any particular assumption on the underlying string dynamics, provided dilaton dominates at early eras after the end of inflation but before Big Bang Nucleosynthesis (BBN). The latter ensures that BBN is not upset by the presence of the dilaton. In this paper, within the context of such a scenario, we study the phenomenology of the constrained minimal supersymmetric model (CMSSM) by taking into account all recent experimental constraints, including those from the LHC searches. We find that the allowed parameter space is greatly enlarged and includes regions that are beyond the reach of LHC. The allowed regions are compatible with Direct Dark Matter searches since the small neutralino annihilation rates, that are now in accord with the cosmological data on the relic density, imply small neutralino-nucleon cross sections below the sensitivities of the Direct Dark Matter experiments. It is also important that the new cosmologically accepted regions are compatible with Higgs boson masses larger than 120 GeV, as it is indicated from the LHC experimental data. The smaller annihilation cross sections needed to explain WMAP data require that the detector performances of current and planned indirect DM search experiments through gamma rays should be greatly improved in order to probe the CMSSM regions.
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