夸克胶子物质内的qq-↑q→qq-↑q反应

夸克胶子物质内的从夸克-夸克-反夸克到夸克-夸克-反夸克的散射过程会影响夸克物质和反夸克物质的热平衡化，其散射振幅是研究热平衡化的一个基础．依据微扰QCD理论，编制Fortran程序，推导了αs^4阶的各个qq-↑q→qq-↑q散射费曼图的振幅平方和不同费曼图间的干涉项．     

北京谱仪轻奇特强子态研究

 自然界的物质由微观原子构成，原子是由位于中心的原子核与核外电子构成的。在更加微观的尺度上，原子核由核子（质子和中子）组成，核子由夸克组成。夸克是几种基本粒子之一，是构成宇宙的基本单元。物理学家用“味道”来区分不同的夸克，共有6种“味道”，分别是上夸克（u）、下夸克（d）、粲夸克（c）、奇异夸克（s）、顶夸克（t）和底夸克（b）。每一种味道的夸克还存在一个相应的反夸克。     

化学非平衡夸克-胶子物质中等质量双轻子的产生

研究了正在进行化学平衡的富重子夸克-胶子物质的双轻子产生，发现由于产生在RHIC能量 的化学非平衡的富重子夸克-胶子物质冷却慢和高的初始温度，导致中等质量双轻子产生重 大增强.因此，中等质量双轻子的增强可以是夸克-胶子物质形成的信号.同时，这个增强能 补偿由于初始夸克化学势增加引起的双轻子抑制，因而双轻子产额的抑制不再是夸克-胶子 物质产生的信号. 关键词： 化学非平衡夸克-胶子物质 热粲夸克 双轻子     

e~＋e~－湮没中不同味道夸克喷注带电粒子多重数差别

利用“夸克产生律”与“夸克组合律”计算了ｅ＋ｅ－湮没中重夸克喷注事例的带电粒子多重数，结果与实验符合．并与轻夸克喷注事例及平均夸克味道喷注事例的多重数做了比较．     

编外粒子及可能存在的新物质态

从亚夸克物理中允许存在的编外粒子出发，探索了可能存在的双夸克态，双轻子态以及轻子夸克等新物质态，给出了它们的结构性和ＳＵ（３）对称表示。     

可能存在的轻子型夸克态

最近在德国汉堡发现了一种轻子与夸克相结合的新物质－－轻子夸克。本文根据焦－－宫亚夸克模型及亚夸克对的产生与重组合机制，探讨了可能存在的轻子型夸克态。     

夸克胶子混合真空凝聚和Dyson-Schwinger方程

基于夸克传播子的Dyson-Schwinger方程，计算了夸克胶子混合真空凝聚和夸克真空凝聚. 这些凝聚不仅联系着夸克在真空态中的虚度，而且也表征了真空中夸克分布的空间宽度. 真空凝聚的存在直接反映着QCD真空的非微扰结构. 计算表明：上夸克与下夸克的虚度为λ²_u,d=0.7GeV²，奇异夸克的虚度为λ²_s=1.6GeV². 这些结果与许多用完全不同的方法得到的结果一致.     

顶夸克已被发现

顶夸克已被发现１９９５年３月２日，美国费米国家实验室召开学术报告会，正式宣布顶夸克已被发现。在会上，ＣＤＦ和Ｄ０合作组分别报告了它们的实验结果。ＣＤＦ测得顶夸克质量为１７６±８±１０ＧｅＶ／ｃ２，顶夸克对的产生截面为６．８而Ｄ０测得顶夸克质量为１９９...     

uu→ss过程的胶子交换势与pp→ΛΛ过程的反应截面

本文给出了夸克－反夸克对　湮没和夸克－反夸克对　产生过程的单胶子和双胶子交换势准至Ｐ２／ｍ２级近似的形式，据此推出了ｕｕ→ｓｓ过程的等效位势．应用这个位势在平面波玻恩近似（ＰＷＢＡ）下计算　→　反应的微分截面和总截面，得到了与实验符合得较好的结果．     

超越阿贝尔优势近似和色等离子体的输运系数计算

给出了一种超越阿贝尔优势近似求解夸克胶子等离子体输运方程的方法，并用它计算了夸克、反夸克等离子体的输运系数，讨论了输运系数的非阿贝尔修正．     

Equation of state in hybrid stars and the stability window of quark matter

Properties of hybrid stars with a mixed phase composed of asymmetric nuclear matter and strange quark matter are studied. The quark phase is investigated by the quark quasiparticle model with a self-consistent thermodynamic and statistical treatment. We present the stability windows of the strange quark matter with respect to the interaction coupling constant versus the bag constant. We find that the appearance of the quark–hadron mixed phases is associated with the meta-stable or unstable regions of the pure quark matter parameters. The mass–radius relation of the hybrid star is dominated by the equation of state of quark matter rather than nuclear matter. The contour plots of the maximum mass of the hybrid star are shown in the plane of the coupling constant and the bag constant.     

Parametrization of Fully Dressed Quark Propagator

Based on an extensive study of the Dyson-Schwinger equations for a fully dressed quark propagator in the “rainbow” approximation, a parametrized form of the quark propagator is suggested. The corresponding quark self-energy Σ_f and the structure of non-local quark vacuum condensate <0|:\bar{q}(x)q(0):|0> are investigated. The algebraic form of the quark propagator proposed in this work describes a confining quark propagation, and is quite convenient to be used in any numerical calculations.     

Quark Gluon Condensate,Virtuality and Susceptibility of QCD Vacuum

We study vacuum of QCD in this work. The structure of non-local quark vacuum condensate, values of various local quark and gluon vacuum condensates, quark-gluon mixed vacuum condensate, quark and gluon virtuality in QCD vacuum state, quark dynamical mass and susceptibility of QCD vacuum state to external field are predicted by use of the solutions of Dyson-Schwinger equations in “rainbow” approximation with a modeling gluon propagator and three different sets of quark-quark interaction parameters. Our theoretical predictions are in good agreement with the correspondent empirical values used widely in literature, and many other theoretical calculations. The quark propagator and self-energy functions are also obtained from the numerical solutions of Dyson-Schwinger equations. This work is centrally important for studying non-perturbative QCD, and has many important applications both in particle and nuclear physics.     

核物质和夸克物质的对称能（英文）

对称能表征了同位旋非对称强相互作用物质状态方程的同位旋相关部分,它对于理解核物理和天体物理中的许多问题有重要意义。简要总结了关于核物质和夸克物质对称能研究的最新进展。对于核物质对称能,通过对核结构,核反应以及中子星的研究,目前对其亚饱和密度的行为已有比较清楚的认识,同时,对饱和密度附近对称能的约束也取得了很好的研究进展。但如何确定核物质对称能的高密行为仍然是一个挑战。另一方面,在极端高重子数密度条件下,强相互作用物质将以退禁闭的夸克物质状态存在。同位旋非对称夸克物质可能存在于致密星内部,也可能产生于极端相对论重离子碰撞中。对最近关于夸克物质对称能对夸克星性质的影响以及重夸克星的存在对夸克物质对称能的约束的研究工作进行了介绍,结果表明同位旋非对称夸克物质中上夸克和下夸克可能感受到很不一样的相互作用,这对于研究极端相对论重离子碰撞中部分子动力学的同位旋效应有重要启发。The symmetry energy characterizes the isospin dependent part of the equation of state of isospin asymmetric strong interaction matter and it plays a critical role in many issues of nuclear physics and astrophysics. In this talk, we briefly review the current status on the determination of the symmetry energy in nucleon (nuclear) and quark matter. For nuclear matter, while the subsaturation density behaviors of the symmetry energy are relatively well-determined and significant progress has been made on the symmetry energy around saturation density, the determination of the suprasaturation density behaviors of the symmetry energy remains a big challenge. For quark matter, which is expected to appear in dense matter at high baryon densities, we briefly review the recent work about the effects of quark matter symmetry energy on the properties of quark stars and the constraint of possible existence of heavy quark stars on quark matter symmetry energy. The results indicate that the u and d quarks could feel very different interactions in isospin asymmetric quark matter, which may have important implications on the isospin effects of partonic dynamics in relativistic heavy-ion collisions.     

从流夸克质量到组分夸克质量的动力学过渡的研究

在彩虹近似下用Dyson Schwinger 方程研究了禁闭夸克的传播子, 得到了夸克动力学质量随动量变化的关系, 即得到了从流夸克质量到组分夸克质量的动力学过渡.     

The Effective Degree of Freedom of Low Energy QCD

The adiabatic effective baryon-baryou interactions and dibaryon candidates are studied systematically with three constituent quark models based on different effective degrees of freedom:Glozman-Riska-Brown Goldstone boson exchange model based on constituent quark and Goldstone boson coupling;Fujiwara model based on constituent quark gluon coupling and Nijmegen one-boson exchange;QDCSM based on constituent quark and gluon coupling with quark delocalization and color screening.We find that the three models predicted the similar effective baryon-baryon interactions for roughly two thirds among the 64 states consisted of octet and decuplet baryons.The differences among three models and their separate characteristics are also studied.     

自能函数和夸克的动力学质量(英文)

研究夸克的质量是QCD研究中的一个非常重要问题。因为, 夸克质量是标准模型的基本输入参数, 准确地确定这些参数无论对于唯象的应用还是对于理论的应用都是极其重要的。基于参数化的完全穿衣服的夸克传播子, 研究了自能函数和夸克的动力学质量。理论预言了夸克质量和自能函数, 其结果与文献中的经验值相符合, 也与Dyson Schwinger方程解一致。反过来这也说明了参数化的夸克传播子是成功和可靠的。Study of mass of quark is one of the most important issues in the investigation of QCD. Because masses of quarks are fundamental QCD input parameters of standard Model, and an accurate determination of these parameters is extremely important for both phenomenological and theoretical applications. Based on the parameterized fully dressed quark propagator proposed by us, the theoretical predictions of the masses of quarks are predicted in this short note. The effective quark mass is defined by the scalar self energy function Bf(p2) and vector self energy function Af(p2). The results of our calculations are in agreement with the empirical values used widely in literature and also show that the parameterized form of quark propagator is an applicable and reliable approximation.     

密度依赖口袋常数下奇异物质的热力学自洽处理及其对混合星性质的影响

在MTT口袋模型的基础上采用密度依赖口袋常数,给出了奇异夸克物质的热力学关系,并用于描述奇异夸克物质及混合星内的夸克相,研究了奇异星、混合星的性质.结果表明,密度依赖口袋常数下,奇异夸克物质的压强公式中有一个附加项,而能量密度中则没有,从而保证了系统的热力学自洽性.在新的热力学关系下,奇异夸克物质的状态方程变软,相应的奇异星的引力质量和对应的半径均变小;混合星的状态方程也变软,其质量变小,而对应的半径也变小.说明经热力学自洽处理后该模型对中子星的状态方程及相应的质量-半径关系等都有显著的影响.     

Calculation of Partition Function of QCD at Finite Chemical Potential

In equilibrium statistical field theory, the partition function has fundamental importance. In this paper we propose a direct and general method for calculating the partition function and equation of state of QCD at finite chemical potential. It is found that the partition function is totally determined by the dressed quark propagator at finite chemical potential up to a multiplicative constant. From this a criterion for the phase transition between the Nambu and the Wigner phases is obtained. This general method is applied to two specific cases： the free quark theory and QCD with a model dressed quark propagator having confinement features. In the first case, the standard Fermi distribution at T = 0 is reproduced. In the second case, we apply the conclusion in previous works to obtain the dressed quark propagator at finite chemical potential and find the unphysical result that the baryon number density vanishes for all values of chemical potential. The reason for this result is discussed.     

强子作为非拓扑孤粒子的SU（5）大统—模型（Ⅰ）

提出一种新的包含三代已知轻子与夸克的ＳＵ（５）大统—模型．按本模型，强子可看作由夸克形成的非拓扑孤粒子；轻子与夸克本质上是相同的，它们之间的差别是由对称性自发破缺造成的；在强子内部，夸克质量很小，其性质与已知夸克相同；在强子外部，夸克的性质与已知轻子相同，只是质量很重，并将很快衰变．本文除了定义严格守恒的电荷Ｑ０、费米子数Ｆ０外，还在孤粒子内部定义了近似守恒的内色荷、内电荷、内费米子数．已知ＳＵ（５）大统—模型的（Ｌ－Ｂ）守恒相应于本模型的Ｆ０守恒。