【作者】 梅花；

【导师】 陈洪；

【作者基本信息】 西南师范大学 ， 理论物理， 2004， 硕士

【摘要】 本文在量子场论中基于准势途径的相对论夸克模型中研究了重夸克偶素的性质。目前，由于作为强相互作用基本理论的量子色动力学(QCD)在低能区(大距离)的非微扰效应，各种QCD激发的模型一直被发展来解释强子的性质。夸克势模型是其中重要的模型之一，它不仅能研究强子的基态，而且能研究激发态，但是，源于在中和大距离与QCD真空的复杂结构有关的非微扰特征，还不可能获得整个距离范围内的夸克—反夸克相互作用势。随着重夸克偶素基态和激发态质量实验数据的大量积累，通过理论预期与实验数据的比较，所获得的夸克—反夸克相互作用势的信息是很有趣的。普遍的共识是在低能区传递相互作用的基本单元具有介子的特征，这使得我们有可能通过研究重介子偶素质量谱和衰变来考察夸克—反夸克相互作用在低能区的行为。 首先，在低能区使用的多是反映渐近自由和夸克禁闭的唯象Cornell势，即在短程区域起主要作用的库仑势和在长程区域起主要作用的线性禁闭势之和。如何考虑这个静态势的相对论修正，核心的问题是如何处理夸克-反夸克相互作用的洛仑兹结构。采纳库仑势源于单胶子直接交换，而线性禁闭源于标量和矢量的混合，同时考虑在短程区域与单胶子直接交换起同样作用的同味正反夸克的湮灭，构造了静态夸克-反夸克势到v~2／c~2级次的完全相对论修正，并拟合计算了重介子偶素的能谱，讨论了相对论修正对重介子偶素能级分裂的作用。所得结果与实验上肯定的数据很好地符合。尹 其次，由于夸克势只能唯象地得到，夸克禁闭机制及其对重介子的影响仍在探索之中.由规范场理论的超弦理论所激发的伸缩子一胶子有效藕合，给出了一个新的静态夸克一反夸克势，讨论了此势模型下重介子的自旋平均能谱、轻子衰变和辐射跃迁宽度，并与Cdrn叭势模型所得到的相应结果作了比较. 进一步的工作需要考虑模型本身的完善来达到对重介子性质的更好理解，并将这个势扩展到对重子性质的研究.更多还原

【Abstract】 Heavy quarkonium properties are studied in the relativistic quark model based on the quasipotential approach in the quantum field theory. Since quantum chromodynamics(QCD) is nonperturbative in the infrared region as the basic theory of strong interaction, the potential model as one of various models inspired by QCD has been developed to explain the properties of hadron. At present,a large amount of experimental data on the masses of ground and excited states of heavy mesons has been accumulated. By comparing theoretical predictions with experimental data, one can obtain a valuable information on the form of the qq interaction potential. Such information is of great practical interest, since at present it is not possible to obtain the quark-antiquark(qq) potential in the whole range of distances from the first principles of QCD. In this region it is necessary to account for nonperturbative effects connected with the complicated structure of QCD vacuum. All this leads to a theoretical uncertainty in the qq potential at intermediate and large distances. It is just in this region of intermediate and large distances that most of the basic meson chracteristics are formed. This makes it possible to investigate the low-energy re-gion of strong interaction by studing the spectra and decays of heavy quarkonia.First, the Cornell potential is used widely as phenomenological potentail and takes rather success in explaining the heavy quarkonium properties. The problem is how to consider the relativistic corrections to this potential. Adopting the assummation that the quark interaction is the sum of the usual one-gluon direct exchange and the mixture of linear scalar and vector potentials, we structure the relativistic corrections of order v2/c2to the Cornell potential, including the annihilation potential for the quark and antiquark of the same favors which plays the same role with the one-gluon direct exchange at short distances. The effects of the relativistic corrections on the hyperfine splittings of quarkonium states are discussed, and a good fit to the available experimental data is obtained on heavy quarkonium mass spectra.Second, the quark potential has to be at present determined phe-nomenologically due to QCD nonperturbation and the mechanism of quark confinement is still in search. We obtain a new quark potential from the effective dilaton-gluon-coupling inspired by superstring theory, and by using this static potential, we explore the mechanism of quark confinement through calculations of the spin-average energy levels, the widths of the leptonic decays and radiative transitions for heavy quarkonium. The obtained results are compared with that of the Cornell potenial.Further works are clearly needed to develop the model to reach a better understanding of the heavy meson properties, and to extendinvestigation of baryon properties.更多还原