Beyond the Standard Model Scenarios: Dark Matter and Collider Signals

粒子物理学的标准模型是历史上最成功的科学理论之一。它可以用一些对称原理和一些自然常数来解释广泛的亚原子现象。然而，有很好的理由相信，标准模型并不是关于物质基本结构问题的最终答案。一方面，有关于模型中参数调整的理论问题。另一方面，实验证据，如中微子振荡和暗物质的存在（对星系的形成至关重要）在标准模型中仍然无法解释。人们普遍认为，解决这些难题需要新的粒子和/或新的相互作用的存在。不幸的是，尽管有许多超出标准模型物理学的预测，但没有新粒子或相互作用存在的确凿证据。对于新粒子为何至今未被探测到，有两种可能的解释。首先，它们可能太重，无法在目前的实验中产生。到目前为止，我的大部分研究都集中在这个想法上，在我的新研究项目中，我想重新审视这种可能性，并对所涉及的假设进行仔细的研究（使用新开发的软件），目的是扩大仍可用于新粒子和新相互作用的参数空间。第二种可能性是新粒子是隐藏的，因为它们与普通物质的耦合非常微弱。可能是它们产生的速率太小，或者是它们形成了一个压缩的频谱，也就是说，它不容易产生可观察到的信号。在这种情况下，最有希望的策略是进行更精确的测量，并增加实验中的事件数量（强度边界）以找到它们。我建议在大型强子对撞机中设计一些搜索，通过选择很少受到背景干扰的观测对象，并补充在质子-质子碰撞中搜索，来寻找重离子碰撞中的这些粒子。

The Standard Model of Particle Physics is one of the most successful scientific theories in history. It can explain a wide range of subatomic phenomena in terms of a few symmetry principles and a handful of constants of nature. There are however, very good reasons to believe that the Standard Model is not the final answer to questions about the fundamental structure of matter. On one hand, there are theoretical concerns about the tuning of the parameters in the model. On the other hand, experimental evidence such as the neutrino flavour oscillations and the existence of dark matter (crucial for the formation of galaxies) remains unexplained in the Standard Model. It is widely believed that the solution to these puzzles requires the existence of new particles and/or new interactions. Unfortunately, although many predictions of beyond the Standard Model physics are available, no conclusive proof of new particles or interactions exists. There are two possible explanations as to why new particles may have escaped detection so far. First, they could be too heavy to be produced in current experiments. Most of my research has been concentrated so far on this idea, and in part of my new research project, I would like to revisit this possibility, and perform a careful study of the assumptions involved (using newly developed software), with the purpose of widening the parameter space still available for new particles and new interactions. A second possibility is that the new particles are hidden, because they couple so feebly to ordinary matter. It may be that the rate at which they are produced is too small, or alternatively, that they form a compressed spectrum, that is, one which does not easily yield observed signals. In this case, the most promising strategy would be to make more precise measurements, and to increase the number of events in experiments (intensity frontier) to find them. I propose to devise some searches at the LHC by choosing observables with little interference from the background, and complimentary to searching in proton-proton collisions, to look for these particles in heavy ion collisions.