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

大爆炸和恒星塌缩的核、粒子和弱相互作用物理学

• 批准号: 0400359
• 负责人: George Fuller
• 金额: $ 30.59万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0400359&HistoricalAwards=false
• 关键词: Nuclear; Particle; Weak; Interaction; Physics

The intellectual merit of this project rests on its principal goal: to probe the fundamental physics of nuclei and neutrinos by exploiting the exciting synergy between nuclear physics and neutrino physics on the one hand, and the dynamics/nucleosynthesis of astrophysical environments on the other. The interrelated physics of neutrinos and strong interaction physics/nuclei is at the heart of current theories for the origin of the light nuclei and the baryon/lepton numbers in the early universe, the origin of the heavy nuclei in stellar collapse-based events, the dynamics of supernovae, and potentially even the dark matter/energy problems. Nuclear physics and nuclear astrophysics stand at the contact point of two great current trends in science: (1) the ongoing experimentally driven revolution in neutrino physics; and (2) the startling recent advances in the capabilities of observational astronomy, especially in cosmology. This represents a tremendous opportunity for advancing both fundamental neutrino/nuclear physics and astrophysics and cosmology through their interconnection. The work supported by this project will aim at exploiting this opportunity. In fact, the PI and his graduate students over the last three funding cycles have discovered a number of these connections between fundamental weak interaction/neutrino/nuclear physics and the frontiers of astrophysics, in early universe physics, the physics of gravitational collapse, nucleosynthesis, and especially the possible connections between neutrino ?avor transformation and dynamics/nucleosynthesis. This has proven to be an excellent training ground for graduate students (7 PhD's in 9 years, all of whom have positions in nuclear physics research, and 5 have tenured or tenure track positions) and undergraduates (6 REU undergraduates). This project will enable the continuing training of excellent students. Coupled with the PI's seminars/outreach and publications, this constitutes the broader impact of this project beyond the scientific product. Arguably, the mass-squared differences and vacuum mixing angles (save for 13) of the neutrinos are now measured. A key goal of this project is to assess and calculate the impact of this new knowledge on models for the physics of the early universe, gravitational collapse, and nucleosynthesis. Some neutrino properties, like the CP-violating phase(es) and 13 remain unmeasured. A goal here will be to assess the role of these quantities in astrophysical environments with an eye toward constraints. Ultimately, the full extent of the neutrino mass and mixing spectrum, especially regarding right-handed states remains mysterious. Because the cosmological parameters (e.g., as derived from the Cosmic Microwave Background (CMB) anisotopies) and neutrino properties are so tightly constrained, a positive result in the on-going mini-BooNE experiment, for example, could signal the existence of a light SU(2) singlet 'sterile' neutrino which mixes with active species. This might also signal the existence of a large net lepton number(s) as well as call for a radical overhall of existing models for stellar collapse, heavy element nucleosynthesis, the role of neutrinos in dark matter/energy, and the origin of the baryon number. Observations of Ultra Metal Poor halo stars recently have given us new insight into the r-process which challenge existing models (e.g., the solar system abundance pattern seems to be universal for nuclear masses 100). The PI and his students will direct analytic and numerical calculations toward: (1) an understanding of active-active and active-sterile channel neutrino flavor transformation in the early universe as regards big bang nucleosynthesis and lepton number generation/destruction/limits, CMB derived neutrino mass limits, supernova shock re-heating, r-process nucleosynthesis, the supernova neutrino signal, and all with emphasis on insight into the newly discovered fixed point solution for the nonlinear neutrino-neutrino forward scattering 'background' potential in the active-active neutrino/antimeutrino conversion channel; (2) a further study of neutrino-nucleus interactions in stellar collapse/heavy element nucleosynthesis, including de-excitation of hot nuclei into neutrino pairs and neutrino capture-induced fission, as well as a consistent treatment of the relationship between the high temperature nuclear partition function and the weak strength distribution in nuclei; (3) studies directed toward better constraints on sterile neutrino dark matter from better knowledge of the physics of the QCD epoch in the early universe, from future x-ray observatories, and from the effects of these particles in post-supernova explosion neutron stars, especially the way in which the neutrino potentials which the govern de-coherence production of these heavy states evolve with time; (4) exploring the role of dynamical neutrino mass generation in cosmology; (5) studies of high neutron excess r-process nucleosynthesis with fission cycling.

该项目的智力价值在于其主要目标：一方面利用核物理和中微子物理之间令人兴奋的协同作用，另一方面利用天体物理环境的动力学/核合成，探索原子核和中微子的基础物理。中微子和强相互作用物理/核的相互关联的物理学是当前理论的核心，用于早期宇宙中轻核和重子/轻子数的起源，基于恒星的事件中重核的起源，超新星的动力学，甚至可能是暗物质/能量问题。核物理学和核天体物理学处于两大科学趋势的接触点：（1）中微子物理学正在进行的实验驱动的革命;（2）观测天文学，特别是宇宙学能力的惊人进展。这代表了一个巨大的机会，推进基础中微子/核物理和天体物理学和宇宙学通过它们的相互联系。该项目所支持的工作旨在利用这一机会。事实上，PI和他的研究生在过去的三个资助周期中已经发现了一些基本弱相互作用/中微子/核物理与天体物理学前沿之间的联系，在早期宇宙物理学中，引力坍缩物理学，核合成，特别是中微子之间可能的联系？avor transformation and dynamics/nucleosynthesis.这已被证明是研究生（7博士在9年，所有人都在核物理研究的位置，和5有终身或终身职位跟踪位置）和本科生（6 REU本科生）的优秀培训基地。该项目将使优秀学生得到继续培训。再加上PI的研讨会/宣传和出版物，这构成了该项目在科学产品之外的更广泛影响。可以说，中微子的质量平方差和真空混合角（除了13）现在已经被测量出来了。该项目的一个关键目标是评估和计算这些新知识对早期宇宙物理模型、引力坍缩和核合成的影响。一些中微子性质，如CP破坏相和13仍然无法测量。这里的一个目标是评估这些量在天体物理环境中的作用，并着眼于约束。最终，中微子质量和混合谱的全部范围，特别是关于右手态的范围仍然是神秘的。因为宇宙学参数（例如，由于宇宙微波背景（CMB）的各向异性）和中微子的性质受到严格的限制，例如，正在进行的mini-BooNE实验的阳性结果可能表明存在与活性物质混合的轻SU（2）单线态“无菌”中微子。这也可能表明存在一个大的净轻子数，并呼吁对恒星坍缩、重元素核合成、中微子在暗物质/能量中的作用以及重子数的起源的现有模型进行彻底的总结。最近对超贫金属晕星的观测使我们对r过程有了新的认识，这对现有的模型提出了挑战（例如，太阳系的丰度模式似乎对核质量是普遍的。PI和他的学生将指导分析和数值计算：（1）了解早期宇宙中的主动-主动和主动-惰性通道中微子味转换，包括大爆炸核合成和轻子数产生/破坏/限制，CMB导出的中微子质量限制，超新星激波再加热，r-过程核合成，超新星中微子信号，重点讨论了新发现的中微子-中微子前向散射“背景”势的不动点解;（2）进一步研究了恒星坍缩/重元素核合成中的中微子-核相互作用，包括热核去激发成中微子对和中微子俘获诱发裂变，以及高温核配分函数与核内弱强度分布之间关系的一致处理;（3）通过对早期宇宙QCD时代物理学的更好了解，通过未来的X射线观测站，通过这些粒子在超新星爆炸后中子星中的效应，特别是通过控制这些重态的去相干产生的中微子势随时间演变的方式，研究如何更好地约束无菌中微子暗物质;（4）探讨中微子动力学质量产生在宇宙学中的作用;（5）研究高中子过剩r过程核合成的裂变循环。