Higgs Searches at DZero

长期以来，发现和理解宇宙的组成部分一直是粒子物理学家的目标。多年来，已经形成了对这些构成要素的理论描述，其中描述了基本粒子以及它们如何相互作用。这一理论被称为“标准模型”。尽管这一理论非常成功--许多测量结果非常精确地证实了它的预测--但拼图中仍有缺失的部分。一个特别引人注目的公开问题是质量的起源。在其最简单的形式中，标准模型不允许诸如夸克、电子、介子、光子、胶子等基本粒子具有质量。这是一个真正的问题，因为实验证据压倒性地支持这样一个命题，即其中一些粒子是大质量的。在希格斯、温伯格和萨拉姆等许多人的工作基础上，对这一理论进行了修正，提出了一种称为“自发电弱对称破缺”的机制。也被称为希格斯机制，该理论的预测之一是存在一种名为希格斯玻色子的中性粒子。这并不是唯一的可能性，这是另一类流行的理论，它进一步扩展了标准模型--被称为“超对称”，或简称为SUSY，预测了许多新粒子的存在--其中包括几个希格斯玻色子。通过寻找希格斯玻色子(S)，人们可以找到支持或驳斥这些理论的证据。目前的实验结果排除了质量小于质子115倍的希格斯玻色子的存在。Tevatron-CDF和D-Zero的实验将在没有发现的情况下将这一限制扩大到180左右。这一点很重要，因为理论考虑和间接的实验证据表明，如果标准模型是正确的，或者最简单的超对称形式是正确的，那么希格斯粒子的质量应该小于这个极限。有几种不同的实验签名--或通道--可以用来搜索希格斯粒子。拟议的研究将包括对D-Zero实验在其中一个通道(最敏感的一个)收集的数据集进行详细分析，并将所有单独通道的结果组合在一起。通过综合来自多个通道的结果，我们获得了观测希格斯玻色子的最好机会。

It has long been the goal of particle physicists to discover and understand the building blocks of the universe. Over the years a theoretical description of these building blocks has been developed which describes the fundamental particles and how they interact with one another. The theory is called the 'Standard Model'. Although this theory has been extremely successful - with many measurements confirming its predictions to great precision - there are missing pieces in the puzzle. One particularly compelling open question is that of the origin of mass. In its simplest form the Standard Model does not allow for the fundamental particles such as quarks, electrons, muons, photons, gluons etc to possess mass. This is a real problem since experimental evidence overwhelmingly supports the proposition that some of these particles are massive. A modification to this theory based on the work of many but most prominently, Higgs, Weinberg and Salaam, proposes a mechanism known as 'Spontaneous Electroweak Symmetry Breaking'. Also known as the Higgs mechanism, one of the predictions of this theory is the existence of a neutral particle called the Higgs Boson. This is not the only possibility, another popular class of theories which further extend the Standard Model - called 'Super-Symmetry', or SUSY for short, predict the existence of many new particles - amongst them several Higgs bosons. By searching for Higgs boson(s) one can thus find evidence to support or refute these theories. Current experimental results rule out the existence of a Higgs boson with a mass less than around 115 times that of the proton. The experiments at the Tevatron - CDF and D-Zero will extend this limit to around 180 in the absence of discovery. This is important because theoretical considerations along with indirect experimental evidence suggest that if the Standard Model is correct or the simplest form of Supersymmetry is correct then the Higgs should have a mass less than this limit. There are several different experimental signatures - or channels - which can be used to search for the Higgs. The proposed research will involve the detailed analysis of the data-set collected at the D-Zero experiment in one of these channels (the single most sensitive) and the combination of the results from all the individual channels. By combining the results from many channels the best possible chance for observing the Higgs boson is achieved.