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

每一秒钟，都有数万亿个中微子穿过我们的身体，不留痕迹。另一方面，在宇宙生命的最初几分钟里——从大爆炸到现在138亿年的宇宙历史中，这不过是一眨眼的功夫——宇宙是如此炽热、如此致密，以至于中微子尽管与物质的相互作用很弱，但在宇宙历史的早期时期的动力学中起着重要作用。因此，早期宇宙为研究基础物理学提供了一个有趣的环境，而在地球上的实验室里，这些基础物理学要么很难探测，要么不可能探测。该项目旨在利用即将到来的高精度宇宙学观测的进展，利用早期宇宙的动力学来探索基础物理学。PI将培养本科生研究人员，当他们从事这个有趣的研究领域时，他们将培养各种技能，这些技能在21世纪的职业生涯中很有价值。在进行这项工作时，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。这些模拟将探索受其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影响的中微子的复杂演化。该项目将探索早期宇宙中中微子的量子动力学演化，这种演化是由高温和密集的环境以及大通量的中微子驱动的。量子动力学中微子的演化受其相干的、统一的量子力学行为、高散射率和中微子-中微子相互作用引入的非线性等因素的影响。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动力学以及质子和中子之间的相互转换中起着重要作用。需要对这种行为进行自洽的探索，以了解它对宇宙学观测的影响，以及大爆炸核合成中元素的合成。该项目的目标是解决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状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高精度宇宙观测和高保真理论计算的目标迈进，将宇宙作为研究基础物理的实验室。该项目推进了“宇宙之窗：多信使天体物理学时代”的目标，这是美国国家科学基金会未来投资的十大理念之一。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。

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.