Nuclear, Particle, and Weak Interaction Physics of the Big Bang and Stellar Collapse

该项目支持的研究将深入了解原子核和辐射在极端温度和密度条件下的行为。反过来，这项研究将寻求利用这些见解，为基本粒子的本质提供重要线索，特别是神秘的中微子，以及这些元素是如何在自然界中合成的，例如，在炽热的恒星内部。这些都是重大的科学问题，世界物理学和天文学的很大一部分努力都是为了回答这些问题。例如，最近的实验已经揭示了幽灵般的中微子的一些特性，并且计划中的实验试图揭示更多。该项目的一个目标是更好地理解这些属性对上述重大问题的影响。这需要将人类关于自然的基本理论，即量子力学，打磨成一种能够模拟宇宙提供的极端环境中中微子行为的工具。这个项目的另一个关键产品将是在研究生和本科两级培训年轻的核物理学家。该项目支持的研究将通过利用核物理学和中微子物理学令人兴奋的新发展的交叉点，以及快速推进的天体物理环境探测，一方面用于探测中微子和原子核的基本物理。这项事业的一个关键问题将是研究中微子如何在致密物质中相互作用，以及这些相互作用如何导致中微子改变它们的口味（例如，电子型中微子变成tau型，反之亦然）和/或它们的自旋（例如，左手型中微子变成右手型，反之亦然——如果中微子是马约拉纳的特征，这就等于把中微子变成反中微子）。这是一个非常非线性的问题，因为中微子的味道/自旋决定了中微子如何相互作用，它们如何相互作用决定了味道/自旋的变化。为此，P.I.和他的研究生和本科生将努力：(1)理解和建模在一般介质中控制中微子风味和自旋演化的量子动力学方程；(2)构建各种超新星、恒星坍缩和致密天体并合环境中中微子风味/自旋演化的大规模数值模拟，并评估这种中微子风味物理对这些场所原子核合成前景的反馈；(3)了解核结构、中微子-核相互作用、核配分函数以及高温环境下的弱强度分布。

The research supported in this Project will provide insights into how atomic nuclei and radiation behave in extreme conditions of temperature and density. In turn, this research will seek to leverage these insights to provide important clues about the nature of elementary particles, the mysterious neutrinos in particular, and about how the elements are synthesized in nature, e.g., in the fiery interiors of stars. These are grand science questions and a significant part of the world's physics and astronomy endeavor is directed toward answering them. For example, recent experiments have revealed some of the properties of the ghost-like neutrinos, and planned experiments seek to uncover more. An objective of this Project will be to better understand the implications of these properties for the grand questions described above. This will require honing humanity's fundamental theory of nature, i.e., Quantum Mechanics, into a tool capable of modeling the behavior of neutrinos in the extreme environments provided by the cosmos. Another key product of this Project will be the training of young nuclear physicists, at both the graduate and undergraduate levels. The research supported in this Project will be directed toward probing the fundamental physics of neutrinos and nuclei by exploiting the intersection of exciting new developments in nuclear physics and neutrino physics on the one hand, with rapidly advancing probes of astrophysical environments on the other. A key issue in this enterprise will be studying how neutrinos interact in dense matter and how these interactions may cause neutrinos to change their flavors (e.g., electron type neutrinos changing to tau type and vice versa) and/or their spins (e.g., left-handed to right-handed, and vice versa - if neutrinos are Majorana in character this is tantamount to changing neutrinos to antineutrinos). This is a fiercely nonlinear problem because neutrino flavor/spin determines how neutrinos interact, and how they interact determines how flavors/spin change. To these ends, the P.I. and his graduate and undergraduate students will work toward: (1) Understanding and modeling the quantum kinetic equations which govern neutrino flavor and spin evolution in a general medium; (2) Constructing large-scale numerical simulations of neutrino flavor/spin evolution in various supernova, stellar collapse, and compact object merger environments and assessing the feedback of this neutrino flavor physics on the prospects for the synthesis of nuclei in these sites; (3) Understanding nuclear structure, neutrino-nucleus interactions, nuclear partition functions, and weak strength distributions in high temperature environments.