RUI: Quantum Kinetics of Neutrinos: Studying the Universe at the Interface of Neutrino and Nuclear Astrophysics

每秒，数以万亿计的中微子穿过我们的身体，没有留下任何痕迹。另一方面，在宇宙寿命的最初几分钟--从大爆炸到现在138亿年的宇宙历史中，只是一眨眼的功夫--宇宙是如此的热和如此密集，以至于中微子尽管与物质的相互作用很弱，但在宇宙历史上这个早期时代的动力学中发挥了重要作用。因此，早期宇宙为研究基础物理提供了一个有趣的环境，这些基础物理可能很难或不可能在地球实验室中进行探测。该项目希望利用即将到来的高精度宇宙学观测方面的即将取得的进展，利用早期宇宙的动力学来探索基础物理学。PI将培训本科生研究人员，当他们从事这一有趣的研究领域时，他们将建立各种技能，这些技能对21世纪的一系列职业生涯都有价值。在执行这项工作时，他们将数值模拟天体物理环境中的中微子演化及其对环境的伴随影响。这些模拟将探索中微子的复杂演化，这些中微子受到量子力学性质以及与其他中微子及其环境的许多相互作用的影响。这个项目将探索早期宇宙中中微子的量子动力学演化，在宇宙中，这种演化是由炎热和密集的环境以及中微子的大流量驱动的。量子动力学中微子的演化受其相干的、么正的量子力学行为、高的散射率以及中微子-中微子相互作用引入的非线性的影响。在早期宇宙中--大爆炸后的最初几分钟--这种非线性量子动力学行为在宇宙的动力学以及质子和中子之间的相互转化中扮演着重要的角色。需要对这种行为进行自洽的探索，才能理解它对宇宙学观测结果的影响，以及大爆炸核合成中元素的合成。这个项目的目标是求解早期宇宙中的量子动力学方程，以建立对这种环境中中微子态的非线性量子动力学演化的更广泛的理解，阐明这种演化的反馈，并朝着利用即将到来的预期的高精度宇宙学观测和高保真理论计算的目标，将宇宙视为研究基础物理的实验室。本项目推进了“宇宙之窗：多信使天体物理时代”的目标，未来NSF投资的十大想法之一。这一奖项反映了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。

Every second, trillions of neutrinos pass through our bodies, leaving nary a trace. On the other hand, in the first few minutes of the lifetime of the universe — a mere blink of the eye in the 13.8 billion year history of the universe from the Big Bang to the present day — the universe is so hot and so dense that neutrinos, in spite of the weakness of their interactions with matter, play an important role in the dynamics of this early epoch in the history of the universe. As a result, the early universe provides an interesting environment to study fundamental physics that may be either difficult or impossible to probe in the terrestrial laboratory. This project looks to leverage upcoming advances in upcoming high-precision cosmological observations to use the dynamics of the early universe to explore fundamental physics. The PI will train undergraduate student researchers, and as they engage in this intriguing field of study, they will build various skills that are valuable across a range of 21st century careers. In performing this work, they will numerically simulate neutrino evolution in astrophysical environments along with the concomitant effect on their environment. These simulations will explore the complex evolution of neutrinos that are influenced by their quantum mechanical nature and by many interactions with other neutrinos and their environment. This project will explore the quantum kinetic evolution of neutrinos in the early universe where this evolution is driven by the hot and dense environment as well as large fluxes of neutrinos. The quantum kinetic neutrino evolution is affected by their coherent, unitary quantum mechanical behavior, their high scattering rates, and nonlinearity introduced by neutrino-neutrino interactions. In the early universe — the first few minutes after the Big Bang — this nonlinear quantum kinetic behavior plays an important role in the dynamics of the universe as well as the interconversion between protons and neutrons. A self-consistent exploration of this behavior is needed too understand its effects on cosmological observables as well as the synthesis of elements in Big Bang Nucleosynthesis. The goal of this project is to solve the quantum kinetic equations in the early universe to build a broader understanding of the nonlinear quantum kinetic evolution of neutrino states in this environment, to elucidate the feedback of this evolution, and toward the goal of leveraging upcoming anticipated high-precision cosmological observations complemented by high-fidelity theoretical calculations to treat the universe as a laboratory to study fundamental physics.This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments.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.