Studies of the Quark Gluon Plasma at STAR and CMS at UC Davis

加州大学戴维斯分校 STAR 和 CMS 的夸克胶子等离子体研究

• 批准号: 2209614
• 负责人: Daniel Cebra
• 金额: $ 133.75万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2209614&HistoricalAwards=false
• 关键词: Studies; Quark; Gluon; Plasma; STAR

Quantum Chromodynamics (QCD) is the theoretical framework that describes the strong nuclear force. The fundamental particles that interact via this force are the quarks and gluons that build up protons and neutrons, which in turn build up the nuclei that make up all atoms. This project aims to study the nature of matter at very high temperatures (about a million times hotter than the sun’s core), where nuclear matter reaches a phase called the Quark-Gluon Plasma (QGP). These extremely high temperatures are reached at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), which have produced striking evidence for QGP formation. At RHIC, the UC Davis Nuclear Physics Group (UCD NPG) will study the thermodynamic properties of the transition in the high-density regime, taking advantage of the versatility of the collider to access different regions of the QCD phase diagram, with particular focus on the existence of a critical point. The UCD NPG will study both fixed-target collisions and beam-beam collisions to scan areas of the phase diagram where indications of the critical point have been found. At the LHC, the UCD NPG will use heavy-quark bound states to study the properties of the QGP at the highest available temperatures, made even higher by the upgrade of the LHC energy to 5.5 TeV per nucleon pair. Heavy quarkonium states, such as bottom-antibottom or charm-anticharm, are sensitive to the modification of the QCD potential expected in the QGP phase. This award will support studies of the pattern of modifications for the bottom and charm quark states that allow a characterization of the temperature of the medium and of the changes to the QCD potential in the QGP phase. The UCD NPG will promote science education by reaching out to the broadest possible audiences through the NSF-funded giant-screen film “Secrets of the Universe”, narrated and starring Co-Pi Calderon de la Barca, and which features the students and work from this group. Through public screenings of the film with live Q&A sessions, the UCD NPG group will educate the public about the science done at the LHC and will encourage children, particularly girls and underrepresented kids, to consider pursuing careers in STEM. The UCD NPG will train and mentor REU and UCD undergraduate students throughout the project. The UCD NPG, in its pivotal role pertaining to the RHIC fixed-target program, will conduct a study of collisions that mimic cosmic radiation. Such studies have a direct impact on the NASA space-radiation protection program aimed at understanding and mitigating the effects of cosmic radiation during lengthy space missions.The scope of this project involves studies at RHIC and at the LHC. At the energy range covered by RHIC and the fixed-target program of the STAR experiment, from 3 – 200 GeV, the UCD NPG will study the phase diagram of QCD matter. Analyses of hadron spectra and baryon-number fluctuations will be used to characterize the QCD environment at each measured energy. These studies will enable searches for the conjectured critical point of the phase diagram near the low-end of the energy range scanned by RHIC. This part of the project will advance our knowledge of the existence of such a critical point and its location in the phase diagram of the strong interaction. At the top energy available at the LHC, the UCD NPG will study heavy-quarkonium states with the CMS experiment. The energy upgrade at the LHC, enabling higher energies and luminosities, will allow studies of events with two quarkonia mesons in the same collision. Events where an Upsilon (bottomonium) and J/psi (charmonium) are simultaneously produced will provide a new window to study the QGP, and how the QCD potential affects the formation of these states in the high-temperature, deconfined phase of the strong interaction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

量子色动力学（QCD）是描述强核力的理论框架。通过这种力相互作用的基本粒子是夸克和胶子，它们形成质子和中子，质子和中子又形成构成所有原子的原子核。该项目旨在研究在非常高的温度下（大约比太阳核心热100万倍）的物质的性质，其中核物质达到称为夸克-胶子等离子体（QGP）的阶段。这些极高的温度是在相对论重离子对撞机（RHIC）和大型强子对撞机（LHC）上达到的，它们为QGP的形成提供了惊人的证据。在RHIC，加州大学戴维斯分校核物理组（UCD NPG）将研究高密度区域中过渡的热力学性质，利用对撞机的多功能性来访问QCD相图的不同区域，特别关注临界点的存在。UCD NPG将研究固定靶碰撞和束-束碰撞，扫描相图中发现临界点的区域。在LHC，UCD NPG将使用重夸克束缚态研究最高温度下QGP的性质，LHC能量升级到每个核子对5.5 TeV后，温度会更高。重夸克偶素态，如底-反底或粲-反粲，对QGP阶段预期的QCD势的修改很敏感。该奖项将支持对底夸克和粲夸克态的修改模式的研究，这些修改模式允许表征介质的温度和QGP阶段中QCD势的变化。UCD NPG将通过nsf资助的巨幕电影“宇宙的秘密”，叙述和主演Co-Pi Calderon de la Barca，并以学生和工作为特色，通过接触尽可能广泛的观众来促进科学教育。通过电影的公开放映与现场问答环节，UCD NPG组将教育公众在LHC所做的科学，并将鼓励儿童，特别是女孩和代表性不足的孩子，考虑追求事业干。UCD NPG将在整个项目中培训和指导REU和UCD本科生。UCD NPG在其与RHIC固定目标计划有关的关键作用中，将进行模拟宇宙辐射的碰撞研究。这些研究对美国航天局旨在了解和减轻长期空间飞行任务期间宇宙辐射影响的空间辐射防护方案有直接影响，该项目的范围包括在RHIC和LHC上进行的研究。在RHIC和星星实验的固定靶计划所覆盖的能量范围内，从3 - 200 GeV，UCD NPG将研究QCD物质的相图。强子谱和重子数涨落的分析将被用来描述每个测量能量下的QCD环境。这些研究将使搜索附近的RHIC扫描的能量范围的低端的相图的固定的临界点。这一部分的项目将推进我们的知识存在这样一个临界点，它的位置在相图中的强相互作用。在LHC可用的最高能量下，UCD NPG将用CMS实验研究重夸克偶素态。大型强子对撞机的能量升级，使更高的能量和光度，将允许研究事件与两个夸克介子在同一碰撞。同时产生Upperion（底偶素）和J/psi（粲偶素）的事件将为研究QGP提供一个新的窗口，以及QCD势如何影响这些状态在高温下的形成，强相互作用的解除阶段。这个奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。