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提供有关基本粒子，特别是神秘中微子的性质的重要线索，以及元素在自然界中是如何合成的，例如，在恒星炽热的内部这些都是重大的科学问题，世界上物理学和天文学奋进的一个重要部分就是为了回答这些问题。例如，最近的实验已经揭示了幽灵般中微子的一些特性，计划中的实验试图揭示更多。本项目的目标之一是更好地理解这些性质对上述重大问题的影响。这将需要磨练人类的基本自然理论，即，量子力学，成为一种能够模拟宇宙提供的极端环境中中微子行为的工具。该项目的另一个主要成果是培训研究生和本科生级别的年轻核物理学家。该项目支持的研究将致力于探索中微子和原子核的基础物理学，一方面利用核物理学和中微子物理学令人兴奋的新发展，另一方面快速推进天体物理环境的探测。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味道（例如，电子型中微子变为τ型并且反之亦然）和/或它们的自旋（例如，从左手到右手，反之亦然-如果中微子的性质是马约拉纳，这相当于将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，而它们如何相互作用又决定了味道/自旋如何变化。为此，PI他和他的研究生和本科生将致力于：（1）理解和模拟量子动力学方程，这些方程控制着一般介质中的中微子味和自旋演化;（2）构建各种超新星、恒星坍缩、和紧凑的物体合并环境，并评估这种中微子味物理学对在这些地点合成核的前景的反馈;（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.