Theoretical Nuclear Physics

量子色动力学(QCD)是关于强相互作用子的理论，夸克受到胶子力的限制，形成质子和其他核物理中的重子，以及夸克-反夸克粒子，即介子。胶子也有可能在没有夸克成分的情况下形成被称为胶球的粒子。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子球的可能状态，重点是确定实验以检验我们的理论图景。特别重要的是我们最近对低质量胶子球的预测，我们认为这种胶子球强烈地耦合到被称为西格玛的两π介子共振。我们正在研究粒子的衰减率，这将为胶球/西格玛理论提供测试。在杰斐逊实验室进行其中一些实验测试是可能的。我们还在对波美子进行研究，它的交换长期以来一直被认为是高能弹性和衍射过程的主导。几乎可以肯定的是，波美龙主要是由胶体组成的，最近我们的团队给出了强有力的证据，证明波美龙与胶子球密切相关，包括我们提出的胶球/西格玛。我们将计算西格玛生产的横截面，以测试波美龙的性质。实验可以在洛斯阿拉莫斯实验室和日本提出的50个GeV加速器上进行。使用布鲁克海文实验室的RHIC设备的质子-质子对撞机，将是测量横截面的极佳实验设备。强子在有限密度和温度下的性质也在研究中。我们已经完成了对低于手征相变温度的强子物质的初步研究，手征相变发生在所谓的大爆炸后大约百万分之一秒的宇宙温度。我们将研究瞬子，某些胶子模，对这种相变前后物质性质的影响，并建议在RHIC加速器上进行测试。我们还将在宇宙微波背景的观测研究中调查这种早期宇宙相变的可能证据。这些对核/粒子物理和宇宙学之间关系的跨学科研究使用了凝聚态物理研究中发展起来的场论方法。

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.