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Search for the Higgs Boson at the ATLAS Experiment

在 ATLAS 实验中寻找希格斯玻色子

基本信息

批准号：
PP/E003699/2
负责人：
Sinead Farrington
金额：
$ 15.06万
依托单位：
University of Warwick
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=PP%2FE003699%2F2
关键词：
Search Higgs Boson ATLAS Experiment

项目摘要

Over a century of study has led physicists to develop the Standard Model theory (SM) of the building blocks of matter and the forces among them. This combines the strong force which binds quarks into nuclei, the weak force which explains radioactivity and the electromagnetic force which holds electrons in atoms. To date, it is the most accurately tested scientific theory, verified to a few parts per billion! Given this amazing success you may wonder why scientists have any doubts about the theory. However, one piece is missing: understanding the generation of mass. Despite all of the SM's testable predictions, it cannot predict any particle's mass (and by extension cannot explain your or my weight). This challenge inspires theories ranging from tweaks of the SM, to more outlandish, but possibly true, theories which require a plethora of new particles, possibly accounting for dark matter. In 1964 Peter Higgs, now Edinburgh professor emeritus, proposed an elegant solution to the mass generation problem requiring only one new particle. This 'boson' grabs hold of other particles and the stronger it holds on, the heavier they become. The eponymous Higgs boson has been a holy grail of fundamental science ever since. Although the Higgs boson was devised to generate mass, its own mass is unspecified. Scientists worldwide have searched for it unsuccessfully, ruling out large mass ranges and driving the search to increasingly high energies. Evidence from other precision data now predicts that if the SM Higgs boson exists, it can be found at the Large Hadron Collider (LHC) at the European Centre for Particle Physics (CERN) which will collide protons in a 27km underground ring at unprecedented energies in 2008. There, we should find the long-awaited SM Higgs boson or, possibly, a boson with unexpected properties revealing that more complex dynamics occur in nature, prompting an entire re-think or extension of the SM. If it exists, my proposed programme will discover the SM Higgs boson in the experimentally favoured low mass range. If not, I may find nature's Higgs surrogate. My careful study will identify which of these scenarios is realised. I will search data from the ATLAS experiment at LHC, analysing 10 billion catalogued collisions, a task likened to finding one phone number in a 1000 directories. However, this is no random search since we know how to look for this 'number': we can do the equivalent of finding out the person's surname by looking for known characteristics of the Higgs boson in data! Theoretical understanding of the boson and experimental skill will pinpoint it in the midst of the maelstrom of activity in energetic proton collisions. I will build and lead a team in the Oxford ATLAS group to find the Higgs boson in its decay to two tau leptons or bottom quarks. With careful analysis of the data, these will provide distinctive experimental fingerprints. Simulations show that these decays will yield the five statistical standard deviations 'gold standard' of convincing discovery. The combination of the group's expertise and my in-depth experience from the USA's Tevatron collider will provide a firm foundation for each member of the team to study one element of the signature. For example by homing in on datasets which contain signatures of known particles which decay like the Higgs boson, the identification algorithms can be honed. Finding the tau lepton or bottom quark requires algorithms which I will base on my experience of precision measurements in the bottom quark sector. These studies will characterise the ATLAS hardware enabling us to search the phonebooks of nature which the experiment provides. We cannot be sure that the Standard Model Higgs boson exists, but we can be certain that the hunt for the Higgs will be a fascinating journey whose destination may prove Peter Higgs right, or even more excitingly, that nature is richer and more complex than he imagined.

经过世纪的研究，物理学家们发展出了物质的基本组成部分以及它们之间的作用力的标准模型理论。这结合了将夸克束缚成原子核的强力、解释放射性的弱力和将电子束缚在原子中的电磁力。到目前为止，它是最准确的测试科学理论，验证到十亿分之几！鉴于这一惊人的成功，你可能想知道为什么科学家对这一理论有任何怀疑。然而，有一件事是缺失的：理解质量的产生。尽管SM的所有预测都是可检验的，但它不能预测任何粒子的质量（也不能解释你或我的体重）。这一挑战激发了各种理论，从SM的调整，到更古怪但可能真实的理论，这些理论需要大量的新粒子，可能解释暗物质。1964年，彼得·希格斯（Peter Higgs），现在是爱丁堡大学的名誉教授，提出了一个只需一个新粒子就能解决质量生成问题的优雅方案。这种“玻色子”抓住其他粒子，它抓住的越强，它们就变得越重。从那以后，希格斯玻色子一直是基础科学的圣杯。虽然希格斯玻色子被设计来产生质量，但它自己的质量是未知的。全世界的科学家都在寻找它，但没有成功，排除了大质量范围的可能性，并将搜索推向了越来越高的能量。来自其他精确数据的证据现在预测，如果SM希格斯玻色子存在，它可以在欧洲粒子物理中心（CERN）的大型强子对撞机（LHC）中找到，该对撞机将在2008年以前所未有的能量在27公里的地下环中碰撞质子。在那里，我们应该会发现期待已久的SM希格斯玻色子，或者可能是一种具有意想不到的性质的玻色子，揭示了自然界中发生的更复杂的动力学，促使人们对SM进行全面的重新思考或扩展。如果它存在，我提出的计划将发现SM希格斯玻色子在实验上有利的低质量范围。如果没有，我可能会找到自然界的希格斯替代物。我的仔细研究将确定这些情景中的哪一种会实现。我将在大型强子对撞机上搜索ATLAS实验的数据，分析100亿次编目的碰撞，这项任务相当于在1000个电话簿中找到一个电话号码。然而，这不是随机搜索，因为我们知道如何寻找这个“数字”：我们可以通过在数据中寻找希格斯玻色子的已知特征来找到这个人的姓氏！对玻色子的理论理解和实验技巧将在高能质子碰撞的活动漩涡中找到它。我将在牛津ATLAS小组中建立并领导一个团队，寻找衰变为两个τ轻子或底夸克的希格斯玻色子。通过对数据的仔细分析，这些将提供独特的实验指纹。模拟表明，这些衰变将产生令人信服的发现的五个统计标准差“黄金标准”。该小组的专业知识和我在美国Tevatron对撞机上的深入经验相结合，将为小组的每个成员研究签名的一个元素提供坚实的基础。例如，通过追踪包含已知粒子（如希格斯玻色子）特征的数据集，可以磨练识别算法。寻找τ轻子或底夸克需要算法，我将根据我在底夸克领域的精确测量经验。这些研究将增强ATLAS硬件，使我们能够搜索实验提供的自然电话簿。我们不能确定标准模型希格斯玻色子是否存在，但我们可以肯定，寻找希格斯玻色子将是一次迷人的旅程，其目的地可能会证明彼得·希格斯是正确的，或者更令人兴奋的是，自然界比他想象的更丰富，更复杂。