Theoretical Study of Nucleon Structure and Hadronic Interactions

现在人们知道，构成原子核的中子和质子本身就是由夸克组成的。核物理学中的一个主要问题是，这种夸克子结构是如何在核物理学的可观测物中表现出来的。为了揭示这些夸克效应，我们集中研究近似对称性。这些是自然界的对称性，人们几乎服从，但不完全服从。研究这些对称性是如何被破坏的，以及被破坏的程度，使我们能够检验核物理中的夸克效应。我们特别关注电荷对称性；如果质子和中子之间没有区别，这将是一种精确的对称。我们集中研究高能量下电荷对称的破缺效应，在高能量下物质的夸克结构更为明显。我们还建议研究强相互作用的细节，强相互作用使原子核结合在一起。我们目前专注于“排他”反应（散射反应，所有的最终产物都被观察到）。我们正试图确定描述这些反应的两种等效方法中最有效的一种。另一个被提议的研究领域是对粒子在极小的二维系统中运动时所产生的影响的研究。人们早就知道，像原子和分子这样的粒子既具有粒子性质，又具有波动性质。在大多数情况下，物质的“波动”特性是微小而微妙的影响。在某些系统中，波动效应可以支配观察到的性质。这些效应可以在可见光的“纳米级”系统（尺寸大致为固体中原子之间的尺寸）中看到，或者在厘米级的系统中使用微波。我们与一位从事微波系统实验的物理学家合作进行数值模拟。更广泛的影响包括培训高科技领域的科学家。我们与本科生、研究生和博士后一起开展研究，他们将成为复杂系统的专家，在技术、纯研究、国防、通信和金融等领域应用。最近的博士后中有几名女性，这培养了新的女性科学家。首席研究员（PI）为非科学家提供关于物理学最新进展的研讨会；这些讲座提高了普通民众的科学素养。PI和他的学生们在印第安纳州布卢明顿的一个儿童科学博物馆做志愿者。他目前是印第安纳大学波因特伦理与公共机构中心“科学与美国公共民主”多学科研究的参与者。

It is now understood that neutrons and protons, the constituents of the atomic nucleus, are themselves composed of quarks. A major question in nuclear physics is how this quark substructure is manifested in observables in nuclear physics. To reveal these quark effects, we concentrate on approximate symmetries. These are symmetries of nature that are nearly, but not completely,obeyed. Studying how these symmetries are violated, and by how much, allows us to examine quark effects in nuclear physics. We focus particularly on charge symmetry; this would be an exact symmetry if there were no differences between protons and neutrons. We concentrate on effects of breaking charge symmetry at high energies, where the quark structure of matter is more evident.We also propose to study details of the strong interaction, the interaction that holds the atomic nucleus together. We are currently concentrating on "exclusive" reactions (scattering reactions where all of the final products are observed). We are trying to determine the most efficient of two equivalent ways of describing these reactions. Another area of proposed study is an examination of effects that occur when particles move in extremely small two-dimensional systems. It has long been known that particles like atoms and molecules possess both particle and wave properties. In most cases the "wave" properties of matter are small, subtle effects. In certain systems, the wave effects can dominate observed properties. These effects are seen in "nanoscale"systems (with dimensions roughly those between atoms in a solid) with visible light, or by using microwaves in systems with dimensions in centimeters. We carry out numerical simulations in collaboration with a physicist who conducts experiments on microwave systems. The broader impacts involve training of scientists in high-tech fields. We carry out research with undergraduates, grad students and postdocs, who become expert in complex systems with applications in technology, pure research, defense, communications and finance. Recent postdocs have included several women, and this trains new women scientists. The principal investigator (PI) provides seminars on recent advances in physics for non-scientists; these talks increase scientific literacy in the general population. The PI and his students volunteer for a children's science museum in Bloomington, Indiana. He is currently a participant in a multidisciplinary study of "Science and American Public Democracy" at the Indiana University Poynter Center for Ethics and Public Institutions.