束缚态的理论研究

Many new resonances have been reported by experiments in recent years. Some of them can be described well as the excited states of the ordinary meson or baryon by traditional models, e.g., Ds(2460), but others can not be described by the traditional model, that is , they are not the ordinary bound states we have known, e.g., Zc(3900). Even for the traditional particles, which are believed by most authors, their propertis are different from the descriptions by traditional model, e.g., the theoretical mass of Ds(2317) from potential model is 160 MeV lower than that from experiments. Through the study of these resonances, we can broaden our understanding of QCD, revise the current model about bound state, and through the study of the non-traditional resonances, we can broaden our knowledge of bound state. So in this program, we will study the program of bound state, focus on the new resonances reported by experiments in recent years, present the constitutes, mass, production and decays of these new resonances, try to revise the current models about bound states, broaden our knowledge of bound states.

近些年实验上发现了一些新的共振态，其中有的可以用传统的模型理论解释，即它们是普通介子或重子的激发态粒子，如Ds(2460)；另外一些很难用现有的模型理论解释，即它们不是我们熟知的束缚态粒子，如带电的Zc(3900)。即使被多数人认为是传统粒子的那些粒子，它们的性质也与传统模型的预言差别很大，例如Ds(2317)的质量比势模型预言的质量小160MeV。对于这些新共振态的研究，一方面可以加强我们对量子色动力学的理解，修正现有的模型理论，另一方面通过对非传统束缚态粒子的研究，可以扩展我们对于束缚态的理解。本课题拟开展束缚态的理论研究，研究近些年实验上发现的这些新共振态，给出它们的内部组成、质量、产生、衰变等行为，达到修正现有的模型理论，扩展我们对于束缚态的理解的目的。

本项目采用相对论的贝特-萨皮特方程方法，研究了许多近些年实验上发现的新共振态，例如Ds(2317)、Ds(2460)、D_s(2700)、D_s(2860)、D^*(2600)、D^*(2650)、D_1(2680)、D^*(2760)、D_3(2760)、D_{s3}(2860)、D_{sJ}(3040)、D_J(3000)、X(3940)、X(4160)等等。研究发现，1、很多粒子是现有传统介子的激发态粒子，例如Ds(2317)和Ds(2460)是Ds介子的量子数1+的轨道激发态1P粒子，它们的质量存在翻转现象；D_s(2700)和D_s(2860)是2S-1D混合出的两个态；D_J(3000)是2P宽态1+粒子；X(3940)应该是\eta_c(3S)等等。2、激发态粒子，特别是高激发态粒子的相对论效应很大，此结论适用于双重的粲偶素和底偶素。因此研究高激发态粒子必须采用相对论的模型来处理问题。3、尝试在产额较大的粒子衰变中发现超出标准模型的可能性，结论是困难很大。