CAREER: Towards Particle Physics Discoveries With Double Cascades In IceCube and Beyond

粒子物理学在上个世纪通过探索新的、不断增加的能量尺度而取得了进步;更普遍地说，物理学通过在新的、未探索的条件下研究物理现象而取得了进步。通过观察三种类型的中微子，电子，μ子和τ子可以改变味道，即自发地从一种变成另一种，发现所谓的无质量中微子实际上有质量，这是其中一种现象。这一意外和无法解释的观察表明，中微子的研究将产生更多的发现。该项目的PI旨在探索尚未涉足的领域和背景中的中微子，以精确测量中微子相互作用并发现新的物理学。南极的冰立方中微子天文台允许研究中微子，其质心能量与瑞士欧洲核子研究中心的大型强子对撞机相当，其从生产到检测的穿越距离可以高达千兆秒差距（千兆秒差距等于32.6亿光年）。利用这些独特的中微子，PI将通过测量τ中微子的出现来研究天体物理尺度上的中微子味道变化，τ中微子可以通过其特征光发射与其他中微子种类区分开来，并将在中微子相互作用中寻找重粒子的产生。从遥远的高能天体物理源测量τ中微子表明，中微子味道的变化，这是一个纯粹的量子力学现象，在宇宙尺度上运作。此外，PI将首次测量高能中微子相互作用中产生的重粒子，这对质子的夸克含量和新中微子物种的存在具有影响。在该项目的实施过程中，PI还将为物理教育和服务不足的社区做出重大贡献。首先，PI将扩展他目前的本科粒子物理课程，以纳入计算物理的元素。这些活动补充了数据分析课程，并使学生接触到现代模拟和重建技术。其次，利用他流利的西班牙语，PI将扩大与当地中学的现有工作，让西班牙裔学生接触中微子物理。该项目包括一项用西班牙语向中学生和教员提供介绍性讲座的计划。西班牙语本科生和研究生将参与推广活动，并将制作关于我们项目物理学的西班牙语教育视频。有了这个奖项，PI计划显着提高天体物理学τ中微子的选择效率，并首次测量高能大气中微子相互作用中D介子的产生。对τ中微子的观测至关重要，因为它们主要来自天体物理学，并证明中微子振荡在宇宙基线上运行。测量D介子的产生将限制质子的奇异夸克含量。此外，PI将首次搜索在亚TeV能量范围内大气中微子相互作用中产生的重中微子。这些重中微子是MiniBooNE实验观察到的无法解释的过量事件的主要解释之一。这些分析通过IceCube中常见的双级联签名联系在一起，PI建议通过开发图形神经网络来识别。该项目还准备PI对NSF资助的和目前正在建设中的IceCube-Upgrade进行后续分析，并在较长的时间尺度上优化IceCube-Gen 2设计，使其继续拥有强大的粒子物理计划。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Particle physics has progressed over the last century by exploring new, increasing energy scales; more generally, physics has moved forward by studying physical phenomena under new, unexplored conditions. The discovery that the supposedly massless neutrino actually has a mass, inferred through the observation that the three types of neutrinos, electron, muon, and tau can change flavor, i.e. spontaneously change from one to another, is one of those phenomena. This unexpected and unexplained observation suggests that the study of neutrinos will yield additional discoveries. The PI of this project aims to explore neutrinos in yet uncharted territories and contexts to make precision measurements of neutrino interactions and discover new physics. The IceCube Neutrino Observatory at the South Pole allows studying neutrinos whose center-of-mass energy is comparable to the Large Hadron Collider at CERN, Switzerland, and whose traversed distance from production to detection can be as large as gigaparsecs (one gigaparsec equals 3.26 billion light years). Using these unique neutrinos, the PI will study neutrino flavor changes in astrophysical scales by measuring the appearance of tau neutrinos, which can be differentiated from other neutrino species by their characteristic light emission and will search for the production of heavy particles in neutrino interactions. The measurement of tau neutrinos from distant, high-energy astrophysical sources demonstrates that neutrino flavor change, which is a purely quantum mechanical phenomenon, operates on cosmic scales. Additionally, the PI will perform the first measurement of heavy particles produced in high-energy neutrino interactions, which has implications for the quark content of the proton and the existence of new neutrino species. During the implementation of this project, the PI will additionally make significant contributions to physics education and underserved communities. First, the PI will extend his current undergraduate particle physics class to incorporate elements of computational physics. These activities complement data analysis classes and expose students to modern simulation and reconstruction techniques. Second, taking advantage of his fluency in Spanish, the PI will expand existing work with a local middle school to expose Hispanic students to neutrino physics. The project includes a plan to deliver introductory lectures in Spanish to middle school students and instructors. Spanish-speaking undergraduate and graduate students will be incorporated in outreach activities and educational videos in Spanish about the physics of our project will be developed.With this award the PI plans to significantly improve the selection efficiency of astrophysical tau neutrinos and measure for the first time the production of D-mesons in high-energy atmospheric neutrino interactions. The observation of tau neutrinos is crucial as they are predominantly of astrophysical origin and prove that neutrino oscillations operate at cosmic baselines. Measuring D-meson production will constrain the proton's strange quark content. Additionally, the PI will perform the first search for heavy neutrinos produced in atmospheric neutrino interactions in the sub-TeV energy range. These heavy neutrinos are one of the leading explanations for the unexplained excess of events observed by the MiniBooNE experiment. These analyses are tied together by their common double cascade signature in IceCube, which the PI proposed to identify by developing a graph neural network. This project also prepares the PI to perform follow-up analyses on the NSF-funded and currently under-construction IceCube-Upgrade and, on a longer timescale, optimize the IceCube-Gen2 design so that it continues to have a strong particle physics program.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.