RUI: Quantum Kinetics of Neutrinos: a window on nuclear and particle astrophysics in the Early Universe and Compact Objects

中微子是一种以光速穿越宇宙的粒子，但很少与物质相互作用。每秒钟都有数万亿个中微子穿过我们的身体而不留痕迹。在炎热和密集的天体物理环境中，大量的中微子显著地相互影响和影响它们的环境。在这里，中微子在能量传输中起着重要的作用，影响着这些环境的动力学，并在质子与中子的转换中起着重要的作用，反之亦然，影响着元素的合成。因此，了解中微子如何演化对于解决天体物理学中有趣的话题至关重要，包括理解元素的起源和使用精确的观测来阐明基础物理学。该项目将培养本科生研究人员，让他们掌握各种技能，这些技能在21世纪的职业生涯中很有价值。他们将数值模拟中微子在天体物理环境中的演化及其对环境的伴随影响。粒子的量子力学性质、中微子与其他中微子的相互作用以及它们碰撞的高速率使这种演化变得复杂。除了指导本科生研究人员外，PI还将通过加强圣地亚哥大学物理学生协会分会开展的外展项目来扩大该项目的影响。这个项目将研究中微子在炎热和密集的天体物理环境中的演化，在这些环境中，中微子的巨大通量会影响其环境的动力学。在这里，中微子的演化是复杂的，因为它们的非线性演化是由于中微子-中微子相互作用，它们的相干，量子力学行为，以及它们的高散射率（动力学），影响上述效应。在早期宇宙，大爆炸后的第一秒内，以及恒星生命的爆炸性结束等环境中，这种非线性量子动力学行为起着重要作用，因为中微子在大长度尺度上传输能量，并控制质子和中子之间的相互转换。为了更好地理解元素的合成，并进行所需的高精度计算，以补充将宇宙作为研究基础物理学的实验室的高精度宇宙学观测，这些效应需要被自我一致地理解。天体物理环境中中微子演化的量子动力学方程是已知的。该项目的目标是在天体物理环境中求解这些方程，从而对中微子状态的非线性量子动力学演化有更广泛的理解，并阐明这种演化对天体物理环境的反馈。该奖项反映了美国国家科学基金会的法定使命，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。

Neutrinos are particles that travel through the universe at the speed of light, but very rarely interact with matter. Trillions of neutrinos pass through our bodies every second without leaving a trace. In hot and dense astrophysical environments, prodigious numbers of neutrinos significantly impact each other and their environment. Here, neutrinos play an important role in energy transport, affecting the dynamics of these environments, and in converting protons to neutrons and vice-versa, affecting the synthesis of elements. Therefore, understanding how neutrinos evolve is essential to addressing intriguing topics in astrophysics, including understanding the origins of the elements and using precise observations to elucidate fundamental physics. The PI will train undergraduate researchers, engaging them in various skills that are valuable across a range of 21st century careers. They will simulate numerically the evolution of neutrinos in astrophysical environments and their concomitant effect on their environment. This evolution is complicated by the quantum mechanical nature of particles, interactions of neutrinos with other neutrinos, and the high rate at which they collide. In addition to mentoring undergraduate researchers, the PI will broaden the impact of this project by enhancing outreach projects run by the Society of Physics Students chapter at the University of San Diego. This project will study the evolution of neutrinos in hot and dense astrophysical environments where prodigious fluxes of neutrinos affect the dynamics of their environment. Here, neutrino evolution is complicated by their nonlinear evolution due to neutrino-neutrino interactions, their coherent, quantum mechanical behavior, and their high scattering rates (kinetics) that influence the aforementioned effects. In environments such as the early universe, within the first second after the Big Bang, and the explosive end of stars' lives, this nonlinear quantum kinetic behavior plays an important role because neutrinos transport energy over large length scales and govern the interconversion between protons and neutrons. These effects need to be self-consistently understood in order to better understand the synthesis of the elements and to perform the high-precision calculations needed to complement high-precision cosmological observations that look to use the universe as a laboratory to study fundamental physics. The quantum kinetic equations for neutrino evolution in astrophysical environments are known. The goal of this project is to solve these equations in astrophysical environments toward toward gaining a broader understanding of the nonlinear quantum kinetic evolution of neutrino states and to elucidate the feedback of this evolution on the astrophysical environments.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.