在极端相对论性原子核碰撞中奇异粒子的演化

在本文中我们用相对论流体力学方程描述了一个膨胀的夸克-胶子等离子体的演化.在此基础上考虑了相变和相变引起的温度效应后,用弛豫方程计算了不同初始温度的奇异粒子的时空分布以及总的奇异粒子数随时间的演化规律,分判定在极端相对论原子核碰撞中是否产生了夸克物质提供了一种理论依据.     

兰州冷却储存环上可开展的强子物理研究

介绍了当前强子物理的研究现状和兰州冷却储存环的能量特点,以及国内强子物理专家的分析和建议。在兰州冷却储存环上,可利用中能轻离子束核反应产生强子激发态研究强子内部夸克态的结构和性质、强子性质随核环境的变化和手征对称破缺与部分恢复。尤其是通过兰州冷却储存环上限能区附近的P＋P反应,研究奇异夸克的不对称性和形状因子,寻找超子激发态和pentaquark的实验证据,发现双重子态的实验事例。 According to both the development on badrons physics and the aspect of Lanzhou cooling storage ring （CSR） and based on the analysis and propositions given by experts in China, we propose some hadrons physics program at CSR. The hadron spectroscopy produced in light nucleus collisions at CSR used to probe the quark and gluon structure of hadrons, to study the modification of the hadron properties in nuclear matter and to investigate the spontaneous breaking of the chiral symmetry and its partial restoration. Especially, the proton-proton collisions at beam energies per proton below 2.8 GeV at CSR should be used to measure the strangeness asymmetry and strange form lector, to probe the existence of hyperon and pentaquarks and to find the evidence for the existence of dibaryon.     

原子核内的夸克效应

这篇评述文章说明了下面四个问题:(i)任何色单态夸克反夸克系统的隐色道一定可以用通常的强子道表示出来,因此任何与隐色道有关的物理总可以用通常的强子自由度来解释;(ii)夸克胶子交换和矢量介子交换产生的重子重子自旋轨道耦合力非常相似,因此不能指望用超核的自旋轨道劈裂来区别夸克胶子交换模型和矢量介子交换模型;(iii)对于破坏电荷独立及电荷对称的重子互作用,电磁作用和夸克质量差同样重要,任何电荷相关互作用的计算必须同时考虑电磁作用和夸克质量差;(iV)和QED中的电子脱局域效应相似,我们猜测对QCD可能有夸克脱囚禁效应并且研究了此效应在双重子系统中的表现。     

铜-铜对撞产生更多的奇异性

在铜离子对撞中,每个核子产生的奇异夸克比更重的金离子对撞要多很多．这是在美国BNL实验室的相对论性重离子对撞机RHIC上物理学家的一项惊人发现．夸克通常被束缚在强子中．预期高能重核碰撞会产生早期宇宙中曾存在过的夸克-胶子等离子体．对夸克一胶子等离子体的研究不仅可以增进对把夸克束缚在一起的强力的了解,而且能提供关于早期宇宙的微观图像．     

200A GeV硫打原子核反应中奇异压低的约化和奇异反重子产生

用事件产生器LUCIAE分析了200AGeV硫打原子核反应中p和Λ产额､横动量分布以及Λ/p比值的NA35数据,结果表明:NA35数据反映了极端相对论性核一核碰撞中青异压低与同能量的核子-核子碰撞相比有约化的现象;但是核-核碰撞中Λ/p比值趋向1,并不必然意味着夸克的味对称性.     

五夸克态进展

对2003年和2004年强子物理研究中的热点——五夸克态,从实验进展和理论研究上进行了较为详细的介绍,对研究的现状进行了评价和展望,同时介绍了国内一些研究小组在五夸克态研究中做出的贡献.     

Quark Mass Dependence of Nucleon Magnetic Moment and Charge Radii

Understanding hadron structure within the framework of QCD is an extremely challenging problem. Our purpose here is to explain the model-independent consequences of the approximated chiral symmetry of QCD for two famous results concerning the quark structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.     

高能复合粒子散射中的夸克自由度

本文提出了一个夸克-强子混合模型来描述高能复合粒子的散射,在此模型中,夸克部分的参数是由符合p-p散射实验来确定的,我们应用这个没有任何自由参数的模型讨论了p-α弹性散射.结果表明,我们的模型大大地改善了以前各种不同理论的计算,并且很好地解释了实验数据.结果还表明,在NN相互作用中的夸克自由度在改善实验数据的理论描述中起着十分重要的作用.     

NuTeV反常与奇异夸克反夸克不对称性

总结了利用核子内的奇异夸克反奇异夸克不对称性来解释NuTeV反常的工作,表明奇异夸克反奇异夸克不对称性可作为解释NuTeV反常的一种合理机制,也说明了NuTeV反常现象也可能是对奇异夸克反奇异夸克不对称性的一种支持。This talk summarized the results of using strange quark-antistrage quark asymmetry of the nucleon to explain the NuTeV anomaly. It is shown that asymmetric strange quark-antistrage quark distributions may be a reasonable explanation for the NuTeV defect. On the other side, the NuTeV anomaly could be the evidence for the existence of asymmetric strange-antistrange quark distributions.     

重子中七夸克成分qqq(q¯q)2 的低位能谱

在非相对论夸克模型内,利用手征超精细相互作用,把原来对五夸克系统qqqq¯q 能谱的预言,扩展到了七夸克系统qqq(q¯q)2 的基态和轨道第一激发态能谱的计算,所使用的参数也是来自于五夸克系统。预言了最低七夸克态的能量大约是2.1 GeV,自旋-宇称是JP =1/2+或者JP =1/2-。由于在这个能区也存在一些三夸克系统和五夸克系统,所以能量在2 GeV 以上的重子激发态可能是这3 种夸克成分的混合。The low-lying energy spectra of 7-quark systems qqq(q¯q)2 is investigated with the schematic flavor-spin interaction, as an extension of the qqqq¯q five quark model. The lowest qqq(q¯q)2 state with an approximate energy 2.1 GeV and the spin-parity JP =1/2+ or JP =1/2-, has been predicted with the parameters used in the five quark system.Because of the overlap with the corresponding qqq and qqqq¯q states above 2 GeV, it is possible for the high excited baryon-resonances to have substantial qqq(q¯q)2 admixtures.     

Multi-strange systems in relativistic mean fields

Characteristics of multi- hypernuclei are investigated within the relativistic mean-field theory. Both linear and nonlinear models and a variety of couplings fitted to ordinary hypernuclei have been investigated. All the parametrizations used in the present work predict qualitatively similar dependence of the studied quantities (rms radii, binding energies, densities) on a number of hyperons.Deceased on May 5, 1991     

原子核模型的研究

到目前为止,物理学家提出了许多原子核模型.最著名的有:1932年费米提出的气体模型的原子核结构;1935年由N·玻尔和费伦克尔提出的液滴模型;1949年由迈耶夫人和简森各自提出的壳层模型;由A·玻尔和莫特尔逊于1953年提出的集体模型(综合模型).本人认为,原子核的结构应为磁场结构模型.下面就对这一结构模型进行说明.1原子核内的质子问的受力分析     

高激发态核的多重碎裂

中能重离子反应后期高激发态核的多重碎裂可用量子统计模型来处理．不稳定的中等质量碎片将再次衰变成新的碎片多重性分布．由反应所发射的各种带电粒子数目间的比率所标志的碎裂度可确定系统的熵,而由粒子不稳定碎片衰变的产额,可确定核系统的温度。 Multifragmentation in the late stages of intermediate-energy heavy ion collisionscan be described with the quantum statistical model. Instable medium fragments undergodecay subsequently, and which would redistribute multi fragment yields. The degree of dissociation, which can be measured by ratios of various charged particles emitted, is proposedas a measure of the entropy of the system. From the yields of the decay of particalinstablefragments to extract the temperature of the system is discussed.     

强子结构与核结构

本文列举了核内存在非核子自由度的证据;论证了核结构的研究必须突破传统的框架,进入到核子及介子的内部结构,才能对原子核内部运动有深入的了解.本文还扼要论述了核物理研究的现状与前景. This paper presents some important experimental evidences of non-nucleonic degrees of freedom in nuclei.From these evidences,the nuclear structure research must go be- yond the traditional framework of nuclear research.To get deeper understanding of the nucle- us,one has to go to the internal structure of hadrons.The present status and future prospects of this new development in nuclear physics are also dicussed briefly.     

热核多重碎裂研究

本文对单体热核多重碎裂的理论与实验研究的国内外现状进行了评述;特别对国内近年来做出的实验结果进行了报导． A summary status of experimental and theoretical research in multi-fragmentation of single hot nucleus both in home and abroad is reviewed, especially some experimental results performed at Lanzhou recently are reported in detail.     

Relativistic Fermi-Gas Model for Nucleus

Spin-half fermions are considered to be limited in a spherical potential well with periodic boundary conditions. The whole system is treated like a relativistic Fermi Gas. Solving the corresponding Dirac equation, the density of states, the Fermi energy, the average energy, the density of states of nucleons and the total energy of the ground-state are obtained.     

超重复合核的存活概率

考虑角动量相关性的情况下计算了超重核259Db的裂变位垒Bf.计算了258Rf,259Db,266Hs和267Mt 4个超重核单中子蒸发的存活概率Wsur及其随角动量分波的变化关系.给出了中子蒸发宽度、裂变宽度和超重核蒸发一个中子的概率对激发能与角动量分波的依赖关系. Considering the dependence on angular momentum， the fission barriers of super heavy nuclei 259Db have been calculated. The survival probability for 258Rf， 259Db，266Hs，267Mt compound and its relation with angular momentum have been estimated. The neutron emission width， the fission width and the realization probability for one neutron emission and their relation with excitation energy and angular momentum are also presented.     

Multi-strange baryon elliptic flow in Pb-Pb collisions at \sqrt {s_{NN} } = 2.76 TeV measured with the ALICE detector

We present the results on elliptic flow with multi-strange baryons produced in Pb-Pb collisions at $\sqrt {s_{NN} } $ = 2.76 TeV. The analysis is performed with the ALICE detector at LHC. Multi-strange baryons are reconstructed via their decay topologies and the v ₂ measurements are analyzed with the two-particle scalar product method. The p _T differential v ₂ values are compared to the viscous hydrodynamical (VISH2+1) model calculation and to the STAR measurements in Au-Au collisions at $\sqrt {s_{NN} } $ = 200 GeV. We found that the model describes ?? and ??v ₂ measurements within uncertainties. The differential v ₂ of ?? and ?? is similar to the STAR measurements at 200 GeV in Au-Au collisions.