Studies in Charm Physics

魅力物理学研究

• 批准号: 0853202
• 负责人: Edward Thorndike
• 金额: $ 108.6万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-15 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0853202&HistoricalAwards=false
• 关键词: Studies; Charm; Physics

The Standard Model (SM) has been successful at describing all relevant experimental phenomena and, thus, has been generally accepted as the fundamental theory of elementary particle physics. Despite its success, the SM leaves many unanswered questions.These can be classified into two main categories: one for subjects related to possible new physics at unexplored energy scales and the other for physics mostly related to Quantum Chromodynamics (QCD), the fundamental theory of the strong interactions.The SM describes particle physics up to energies of around 100 GeV (Giga electron Volts). It is expected that new particles and new interactions will appear at some higher energy scale, say 1 TeV (Tera electron Volts) . Those new particles and new interactions are presumably needed to solve some inconsistencies within the SM and for the ultimate unification of all interactions. Such physics issues all belong to the first category, and will be addressed by experiments at the LHC, which will start operation in 2008. The second category of unanswered questions includes those requiring QCD. QCD, as the fundamental theory of the strong interactions, is well tested at short distances, but at long distances so-called nonperturbative effects become important and these are not well understood. These effects are very basic to the field of particle physics and include e.g., the structure of hadrons (particles with strong interactions) and the spectrum of hadronic states. Lower energy facilities with high luminosity can address these questions. Among these, the Beijing Electron Positron Collider II (BEPCII), which will operate in the 2 GeV to 4.6 GeV energy range, will be an important contributor. This is because it spans the energy range where both short-distance and long-distance effects can be probed.BES III is a general-purpose detector based at the BEPCII e+e- collider in China. BEPCII has a 100x improvement in its luminosity over its predecessor,There has also recently been a renewal of interest in the subjects of hadron spectroscopy and charm quark physics. This renaissance has beendriven in part by experimental reports of charm particle mixing and the discovery of additional narrow-width charm states, plus a plethora of charmonium-like states at the B meson factories. At the same time, a computer intensive technique called lattice Quantum Chromodynamics (QCD) is now coming of age, and we are entering a new era when precise, quantitative predictions from lattice QCD can be tested against experimental measurements. The BES-III experiment at the BEPCII collider in Beijing, which started operation in summer 2008, will accumulate huge data samples relating to these topics. Coupled with currently available results from the (closing) CLEO-c experiment, BES-III will make it possible to study in detail, and with unprecedented high precision, light hadron spectroscopy in the decays of charmonium states and charmed mesons. Many high precision measurements will be accomplished. BES-III analyses are likely to be essential in deciding if recently observed signs of charm mixing are actually due to new physics or not. And precision lattice QCD calculations provide the opportunity to probe the charged Higgs sector in some mass ranges that will be inaccessible to the LHC.

标准模型（SM）已经成功地描述了所有相关的实验现象，因此被普遍接受为基本粒子物理学的基础理论。尽管取得了成功，SM 仍然留下了许多未解答的问题。这些问题可分为两大类：一类是与未探索的能量尺度上可能出现的新物理学相关的学科，另一类是主要与量子色动力学 (QCD) 相关的物理学，量子色动力学是量子力学的基本理论。 SM 描述了能量高达 100 GeV（千兆电子伏特）的粒子物理学。预计新粒子和新相互作用将出现在更高的能量尺度，例如 1 TeV（太拉电子伏特）。可能需要这些新粒子和新相互作用来解决 SM 内的一些不一致问题并最终统一所有相互作用。这些物理问题都属于第一类，将通过大型强子对撞机的实验来解决，该大型强子对撞机将于2008年开始运行。第二类尚未解答的问题包括那些需要QCD的问题。 QCD 作为强相互作用的基本理论，在短距离上得到了很好的测试，但在长距离上，所谓的非微扰效应变得很重要，但这些效应还没有得到很好的理解。这些效应对于粒子物理学领域来说是非常基础的，包括强子结构（具有强相互作用的粒子）和强子态谱等。具有高亮度的低能源设施可以解决这些问题。其中，运行在2 GeV至4.6 GeV能量范围的北京正负电子对撞机II（BEPCII）将是重要的贡献者。这是因为它跨越了可以探测短距离和长距离效应的能量范围。BES III是基于中国BEPCII e+e-对撞机的通用探测器。 BEPCII 的亮度比其前身提高了 100 倍，最近人们对强子光谱学和粲夸克物理的兴趣也重新燃起。这种复兴在一定程度上是由粲粒子混合的实验报告和其他窄宽粲状态的发现以及 B 介子工厂中大量的类粲状态所推动的。与此同时，一种称为晶格量子色动力学 (QCD) 的计算机密集型技术现已成熟，我们正在进入一个新时代，可以根据实验测量来测试晶格 QCD 的精确定量预测。 2008年夏天开始运行的北京BEPCII对撞机上的BES-III实验将积累与这些主题相关的大量数据样本。结合目前已结束的 CLEO-c 实验的结果，BES-III 将使以前所未有的高精度详细研究粲素态和粲介子衰变的光强子光谱成为可能。将完成许多高精度测量。 BES-III 分析可能对于确定最近观察到的魅力混合迹象是否实际上是由于新物理学造成的至关重要。 精确的晶格 QCD 计算提供了在大型强子对撞机无法访问的某些质量范围内探测带电希格斯扇区的机会。