Theoretical Study of Nucleon Structure and Hadronic Interactions

现在人们知道，原子核的成分中子和质子本身就是由夸克组成的。核物理中的一个主要问题是这种夸克子结构是如何在核物理中的可见项中表现出来的。为了揭示这些夸克效应，我们集中在近似对称性上。这些是自然的对称性，几乎，但不是完全遵守的。研究这些对称性是如何被破坏的，以及被破坏的程度，使我们能够检查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差别，这将是一个精确的对称性。我们集中在高能下打破电荷对称性的影响，其中物质的夸克结构更加明显。我们还建议研究强相互作用的细节，即将原子核聚集在一起的相互作用。我们目前专注于“排他性”反应(可以观察到所有最终产物的分散反应)。我们正试图确定描述这些反应的两种等价方式中最有效的一种。拟议研究的另一个领域是对粒子在极小的二维系统中运动时产生的影响进行检查。人们很早就知道，像原子和分子这样的粒子既具有粒子性质，又具有波性质。在大多数情况下，物质的“波”性质是微小的、微妙的效应。在某些系统中，波的影响可以支配观察到的性质。这些效应在具有可见光的“纳米级”系统(其尺寸大致相当于固体中原子之间的尺寸)中可以看到，或者在尺寸为厘米的系统中使用微波。我们与一位在微波系统上进行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、研究生和博士后开展研究，他们成为复杂系统方面的专家，在技术、纯研究、国防、通信和金融方面的应用。最近的博士后包括了几名女性，这培养了新的女性科学家。首席研究员(PI)为非科学家提供有关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。这位少年派和他的学生为印第安纳州布鲁明顿的一家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和公共机构中心一个多学科研究的参与者，该研究主题是“科学与美国公共民主”。

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.