Physics at the LHC with CMS

大型强子对撞机 (LHC) 的物理与 CMS

• 批准号: 1506406
• 负责人: Paul Sheldon
• 金额: $ 99万
• 依托单位: Vanderbilt University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-15 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506406&HistoricalAwards=false
• 关键词: Physics; LHC; CMS

One of the major intellectual achievements of the 20th century was the development of the Standard Model (SM) of particle physics. This model succeeded in classifying all of the elementary particles known at the time into a hierarchy of groups having similar quantum properties. The validity of this model to date was recently confirmed by the discovery of the Higgs boson at the Large Hadron Collider at CERN. However, the Standard Model as it currently exists leaves open many questions about the universe, including such fundamental questions as to why the Higgs mass has the value it has. The Large Hadron Collider (LHC) is the premier Energy Frontier particle accelerator operating at the CERN laboratory near Geneva Switzerland. It is currently one of the foremost facilities for answering these Beyond the Standard Model questions and studying the properties of the Higgs boson. One of the primary functions of the Compact Muon Solenoid (CMS) experiment at the LHC is to discover new physics beyond the Standard Model. The work proposed here will analyze data from the CMS experiment looking for signals of Beyond the Standard Model (BSM) physics. This award will fund two aspects of the CMS experiment: 1) further searches for BSM physics and 2) help build the CMS Phase I forward pixel detector (FPix) upgrade, which will enhance the ability of CMS to discover BSM physics. BSM theoretical predictions include several different new particles in the so-called Super Symmetric (SUSY) theory. These new particles are candidates for Dark Matter. This award will fund searches for SUSY via the decays to multiple leptons (electrons or muons) and jets (the experimental signature of quarks). The SUSY particle decays in these channels also include a SUSY particle that goes right through the detector without interacting, thus the event has missing energy. Many SUSY models have been ruled out by the analysis of LHC data from 2010-2013. With the new higher energy running at LHC starting summer 2015, new analysis techniques will be applied in order to separate out SUSY (or other Dark Matter candidates) signals from large backgrounds. This involves the Vector Boson Fusion (VBF) mode of production where the quark-quark collision produces a pair of vector bosons (either W or Z) which then interact (Fuse) to form new particles. The experimental signature of this VBF production is a pair of energetic jets in the forward direction in opposite hemispheres of the detector, with large di-jet mass. These jets stand out above background from SM particle decays and thus enhance the signal to background ratio in the possible discovery of BSM particles. The award also provides important parts of the FPix upgrade which are being tested at FermiLab. The CMS Forward pixel upgrade will allow the precise vertex location, needed for all physics studies, even in the harsh environment (very high luminosity) expected in near future LHC running. The CMS Forward Pixel Detector uses state-of-the art silicon technology for particle detection combined with equally sophisticated readout electronics. Innovative techniques of radiation hard technology and bump bonding have been used in the current detector to meet the real estate challenges in a high radiation environment. These techniques would greatly enhance the life span of detectors used in outer space research and improve bio-sensing miniature devices for medical applications.

世纪的主要学术成就之一是粒子物理学标准模型（SM）的发展。该模型成功地将当时已知的所有基本粒子分类为具有相似量子特性的组的层次结构。最近，欧洲核子研究中心的大型强子对撞机发现了希格斯玻色子，证实了这一模型的有效性。然而，目前存在的标准模型留下了许多关于宇宙的问题，包括为什么希格斯质量具有它的价值等基本问题。大型强子对撞机（LHC）是在瑞士日内瓦附近的欧洲核子研究中心实验室运行的首要能源前沿粒子加速器。 它是目前回答这些超越标准模型问题和研究希格斯玻色子性质的最重要的设施之一。LHC的紧凑μ子螺线管（CMS）实验的主要功能之一是发现标准模型之外的新物理。本文提出的工作将分析CMS实验的数据，寻找超越标准模型（BSM）物理的信号。该奖项将资助CMS实验的两个方面：1）进一步搜索BSM物理; 2）帮助构建CMS第一阶段前向像素检测器（FPix）升级，这将增强CMS发现BSM物理的能力。 BSM理论预测包括所谓的超对称（SUSY）理论中的几种不同的新粒子。这些新粒子是暗物质的候选者。该奖项将资助通过衰变到多轻子（电子或μ子）和喷流（夸克的实验特征）来寻找超对称性。 这些通道中的超对称粒子衰变还包括一个直接穿过探测器而没有相互作用的超对称粒子，因此事件具有丢失的能量。通过对2010-2013年LHC数据的分析，许多超对称模型已经被排除。随着2015年夏季LHC开始运行新的更高能量，新的分析技术将被应用于从大背景中分离出超对称（或其他暗物质候选者）信号。这涉及到矢量玻色子融合（VBF）的产生模式，其中夸克-夸克碰撞产生一对矢量玻色子（W或Z），然后相互作用形成新的粒子。这个VBF生产的实验签名是一对充满活力的喷流在向前的方向在相反的半球的检测器，大di-jet质量。这些喷流从SM粒子衰变的背景中脱颖而出，从而提高了可能发现BSM粒子的信号与背景比。该奖项还提供了正在费米实验室测试的FPix升级的重要部分。CMS Forward像素升级将允许所有物理研究所需的精确顶点位置，即使在不久的将来LHC运行所预期的恶劣环境（非常高的光度）中。CMS正向像素检测器采用先进的硅技术进行粒子检测，并结合同样复杂的读出电子设备。目前的探测器采用了抗辐射技术和凸点键合等创新技术，以满足高辐射环境下的真实的房地产挑战。这些技术将大大提高外层空间研究中使用的探测器的寿命，并改进用于医疗应用的微型生物传感装置。