Searching and Discovering New Physics with Run-2 on ATLAS Experiment of LHC

基本粒子物理的标准模型(SM)很好地描述了强相互作用和弱电相互作用，即影响质子和中子等基本粒子的结构和行为的力。SM还描述了我们所知道的关于宇宙中可见物质的大部分。在瑞士大型强子对撞机(LHC)上发现的希格斯玻色子是这一理论的最后一个组成部分。然而，SM的压倒性成功似乎只是强调了它的局限性。还有许多悬而未决的问题。为什么有三种夸克，组成质子和中子的基本粒子，以及轻子，基本粒子，如电子和µ子？时空本身的本质是什么？弦理论和弦启发模型提出的额外维度真的存在吗？暗能量和暗物质在我们目前的宇宙图景中处于什么位置？这些关键问题的答案只能通过包括SM之外的新物理学来找到。该小组将与大型强子对撞机的ATLAS实验合作，通过寻找质子-质子碰撞中出现的新粒子来寻找这种新的物理学。这个项目的一个令人兴奋的特点是，来自弗雷斯诺和其他加州州立大学的一些本科生和硕士学生将参与其中。他们不仅将参与这一分析推力，还将从其他ATLAS合作者那里获得帮助各种硬件项目的实践经验。在这项拟议的研究计划中，加州州立大学弗雷斯诺分校的高教授和他的团队将继续在双喷流事件中从新物理学中寻找粒子。使用双喷流数据作为寻找新物理的一种方法是一种具有悠久历史的经典方法，需要精确地了解SM预期的喷流能量标度。PI在喷气物理方面有相当丰富的经验，并很清楚这带来的挑战。他打算建立在成功的先前工作的基础上，在这些工作中，识别出了新的变量，这些变量应该可以区分潜在的新物理信号和QCD。这些变量通过构造，在对观察到的结构进行多变量分析时使用来自部分子的辐射模式。

The Standard Model (SM) of elementary particle physics gives an excellent description of the strong and electroweak interactions, the forces that influence the structure and behavior of elementary particles such as the proton and neutron. The SM also describes most of what we know about the visible matter in the Universe. The Higgs Boson, discovered at the Large Hadron Collider (LHC) in Switzerland, was the last ingredient in this theory. Yet the overwhelming success of the SM seems only to emphasize its limitations. There are many open questions remaining. Why are there three families of quarks, elementary particles that make up the proton and neutron, and leptons, elementary particles such as the electron and muon? What is the nature of space-time itself? Do the extra dimensions suggested by string theories and string- inspired models really exist? Where do dark energy and dark matter fit into our current picture of the universe? Answers to these key questions can only be found by including new physics beyond the SM. This group will work with the ATLAS experiment at the LHC to look for this new physics by searching for new particles emerging from proton-proton collisions. An exciting feature of this program is that a number of undergraduate and Masters students from Fresno and other Cal State institutions will be involved. They will participate not only in this analysis thrust but will also gain hands-on experience helping in a variety of hardware projects from other ATLAS collaborators.In this proposed research plan, Professor Gao and his group at California State University, Fresno will continue to search for particles from new physics in di-jet events. The use of di-jet data as a way to search for new physics is a classic approach with a long history, and requires precise understanding of the jet energy scales expected from the SM. The PI has considerable experience in jet physics and is well aware of the challenges this presents. He intends to build on successful prior work in which new variables were identified that should discriminate a potential new physics signal from QCD. Such variables, by construction, use the radiation patterns from partons in a multi-variate analysis of the structures observed.