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展；更广泛地说，物理学通过在新的、未知的条件下研究物理现象而取得了进展。通过观察三种类型的中微子可以改变味道，即自发地从一种中微子改变到另一种中微子，发现所谓的无质量中微子实际上有质量，这就是其中之一。这一意想不到且无法解释的观察表明，对中微子的研究将产生更多的发现。该项目的PI旨在探索未知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可以研究其质心能量可与瑞士欧洲核子研究中心的大型强子对撞机相媲美的中微子，其从产生到探测的穿越距离可达千兆秒(一千兆秒相当于32.6亿光年)。利用这些独特的中微子，PI将通过测量tau中微子的出现来研究天体物理尺度上的中微子味道变化，tau中微子可以通过其特征光发射与其他中微子物种区分开来，并将在中微子相互作用中寻找重粒子的产生。对来自遥远的高能天体物理源的tau中微子的测量表明，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将对高能中微子相互作用产生的重粒子进行首次测量，这对质子的夸克含量和新中微子物种的存在具有意义。在这一项目的实施过程中，国际和平研究所还将为物理教育和服务不足的社区作出重大贡献。首先，PI将延长他目前的本科粒子物理课程，以纳入计算物理的元素。这些练习是对数据分析课程的补充，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将扩大与当地一所中学的现有工作，让拉美裔学生接触中微子物理。该项目包括一项向中学生和教师提供西班牙语入门课程的计划。讲西班牙语的本科生和研究生将被纳入推广活动，并将用西班牙语制作关于我们项目物理的教育视频。通过这一奖项，PI计划显着提高天体物理tau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tau中微子的观测是至关重要的，因为它们主要源于天体物理，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怪夸克含量。此外，PI将首次在亚TeV能量范围内搜索大气中微子相互作用产生的重中微子。这些重中微子是MiniBooNE实验观测到的无法解释的过量事件的主要解释之一。这些分析通过它们在IceCube中的公共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这些签名。该项目还为PI做好准备，以便对NSF资助的和目前正在建设的IceCube升级进行后续分析，并在更长的时间范围内优化IceCube-Gen2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智力优势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.