Theoretical Nuclear Physics

量子色动力学（QCD）是强相互作用的理论，夸克被胶子力限制形成质子和其他核物理重子，以及夸克-反夸克粒子，介子。 胶子也有可能形成没有夸克成分的粒子，称为胶球。 胶球的发现和研究是核/粒子物理学最重要的领域之一。使用QCD，我们正在研究介子和胶球的可能状态，重点是确定实验来测试我们的理论图像。 特别重要的是，我们最近预测的低质量胶球，我们觉得是强烈耦合到一个两π介子共振，称为西格玛。 我们正在研究粒子的衰变率，这将为胶球/西格玛理论提供测试。 在杰斐逊实验室进行这些实验测试是可能的。我们也正在进行调查的Pomeron，其交换早已知道占主导地位的高能弹性和衍射过程。 几乎可以肯定的是，坡密子主要由胶组成，最近我们的小组已经给出了强有力的证据，证明坡密子与胶球密切相关，包括我们提出的胶球/西格玛。 我们将计算σ产生的截面，以检验坡密子的性质。 实验可以在洛斯阿拉莫斯实验室和日本提议的50 GeV加速器上进行。 利用布鲁克海文实验室的RHIC设施的质子-质子对撞机将是实验测量横截面的极好工具。强子在有限密度和温度下的性质也正在研究中。 我们已经完成了在手征相变温度以下的强子物质的初步研究，手征相变发生在所谓的大爆炸后约百万分之一秒的宇宙温度下。 我们将研究瞬子，某些胶子模，对相变之下和之上的物质性质的影响，并提出在RHIC加速器上进行试验的建议。 我们还将在宇宙微波背景辐射的观测研究中调查这种早期宇宙相变的可能证据。 这些核/粒子物理学和宇宙学之间的关系的跨学科研究使用凝聚态物理学研究中开发的场论方法。

Quantum Chromodynamics (QCD) is the theory of strong interactons, with quarks confined by gluonic forces to form protons and other baryons of nuclear physics, as well as quark-antiquark particles, the mesons. It is also possible for the gluons to form particles, called glueballs, without quark constituents. The discovery and study of glueballs is one of the most important areas of nuclear/particle physics. Using QCD, we are investigating possible states of mesons and glueballs with emphasis on identifying experiments to test our theoretical picture. Of particular importance is our recent prediction of a low-mass glueball which we feel is strongly coupled to a two-pion resonance, called the Sigma. We are investigating decay rates of particles which will provide tests of this theory of the glueball/sigma. It is possible to carry out some of these experimental tests at Jefferson Laboratory. We are also carrying out investigations of the Pomeron, whose exchange has long been known to dominate high energy elastic and diffractive processes. It is almost certain that the Pomeron is composed largely of glue, and recently our group has given strong evidence that the Pomeron is closely related to glueballs, including our proposed glueball/sigma. We shall calculate cross sections for sigma production to test the nature of the Pomeron. Experiments could be carried out at the 50 GeV accelerators proposed at Los Alamos Laboratory and in Japan. The proton-proton collider, using the RHIC facility at Brookhaven Laboratory, would be excellent for experimental measurements of the cross sections. Properties of hadrons at finite densities and temperatures are also being investigated. We have completed a preliminary study for hadronic matter at temperatures below the chiral phase transition, which occurs at the temperature of the universe about a millionth of a second after the so-called big bang. We shall study the effect of instantons, certain gluonic modes, on the properties of matter both below and above this phase transition, and propose tests at the RHIC accelarator. We shall also investigate possible evidence for this early-universe phase transition in observational studies of the cosmic microwave background. These interdisciplinary investigations of relationships between nuclear/particle physics and cosmology use field theoretic methods developed in studies of condensed matter physics.