Nuclear Theory: Structure and Reactions

原子核结构的无核壳模型在过去的15年里，我们的研究小组一直在开发一种计算原子核性质的第一原理方法，从质子和中子之间的基本相互作用开始，包括成对的相互作用和三重态相互作用。这种方法成功的关键是将原子核中的所有质子和中子视为活跃的，而不是将其中一些保持静止，即作为惰性核。因此，我们的方法被命名为无核壳模型。通过处理所有活跃的粒子，我们能够准确地计算原子核内部粒子之间的介质修正相互作用，从而能够计算由这些相互作用产生的核结构的细节。除了给出原子核理论性质的微观结果外，我们的形式主义还允许我们分析三个粒子之间相互作用的不同理论模型，即所谓的三核相互作用。理解三核相互作用的本质是目前理论核物理中最基本的问题之一。这种形式也可以用来研究其他物理系统中的三粒子相互作用。为了进行大规模的无核壳层模型计算，我们开发了几个新的壳层模型计算机代码，可以处理多达10亿个单粒子基态。同样，这些计算机代码也应用于解决其他研究领域的重要、突出的问题，如凝聚态物理和化学。我们的研究问题在教育和培训新一代年轻的核结构理论家方面也发挥了重要作用。在我们目前关于无核壳模型的研究过程中，我们在亚利桑那大学培养了五名新的博士核理论家，并培训和指导了六名博士后研究助理。更多的研究生和博士后研究助理参与了我们与美国、欧洲、澳大利亚和突尼斯的其他核理论小组的合作。

The No Core Shell Model for Nuclear Structure Over the last 15 years our research group has been developing a firstprinciples approach for calculating the properties of atomic nuclei,starting from the fundamental interactions among the protons and neutrons,both pairwise and in terms of triplets. The key to the successes of this approach is the treatment of all the protons and neutrons in the nucleus as being active, instead of holding some of them static, that is, as aninert core. Hence, the name of our approach, the No Core Shell Model. Bytreating all particles active, we are able to calculate exactly themedium-modified interaction among particles inside the nucleus and,thereby, the details of the nuclear structure produced by these interactions. Besides giving us microscopic results for the theoretical properties of atomic nuclei, our formalism allows us to analyze different theoretical models for the interactions among three particles, the so-called threenucleon interaction. Understanding the nature of the three-nucleoninteraction is one of the most fundamental problems in theoretical nuclearphysics at this time. This formalism can also be used for investigatingthree-particle interactions in other physical systems. In order to perform our large-scale no-core shell-model calculations, we have developed several new shell-model computer codes, which can handle up toone-billion single-particle basis states. Again such computer codes haveapplications to the solving of important, outstanding problems in other fields of research, such as in condensed matter physics and in chemistry.Our research problem has also played a significant role in educating andtraining a new generation of young nuclear-structure theorists. During the course of our current research program on the no-core shell model, wehave educated five new PhD nuclear theorists and trained and mentored sixpostdoctoral research associates at the University of Arizona. Severalmore graduate students and postdoctoral research associates have been involved our collaborations with other nuclear-theory groups in the USA, Europe, Australia, and Tunisia.