重夸克偶素的强子跃迁理论

我们知道宏观物体是由分子、原子组成的.原子是由电子和原子核组成的.原子核又是由原子和中子组成的.人们对物质徽观结构和微观运动基本规律的不断深入的研究,推动着物理学不断向前发展.近代粒子物理(又称高能物理)的研究,发现质子、中子和与它们相似的超子等(统称为重子)以及与它们有强相互作用的介子(介子和重子统称为强子)还有更深一层的内部结构.它们是由一种称为夸克的更基本的粒子所组成的.已经知道的夸克有以下几种: u c t(所带电荷为质子电荷的2/3), d s b(所带电荷为质子电荷的-1/3),其中u,d,s,b等夸克的存在已有明确的实验根据,t…     

相对论夸克模型对重夸克偶素质量谱的研究

介绍了量子场论中基于准势途径的一个相对论夸克模型,并使用这个相对论夸克模型计算了重夸克偶素的质量谱.显示这个相对论夸克模型可较好地拟合实验上肯定的质量谱数据. A relativistic quark model based on the quasipotential approach in quantum field theory is briefly introduced, and by using this model, heavy quarkonium mass spectra are calculated in detail. It is shown that such a model can give results which are in agreement with the observed experimental data on the mass spectra.     

HERMES五夸克强子态Θ+实验探索

一个新的强子态的实验证据在2?7.6GeV正电子轰击氘靶产生的虚光子产物中被发现.HERMES通过分析衰变道K0sp→π+π–p,在K0sp不变质量谱上质量1528±2.6(stat.)±2.1(sys.)MeV处观察到共振峰.该共振峰可以被解释为理论预言的五夸克强子态Θ+(uudds).而K+p不变质量谱上未能观察到共振预示Θ+很可能是同位旋单态.     

中子星内部强子-夸克相变的有限尺度效应研究

在致密星体内部极高密度条件下,强子物质可能发生退禁闭相变成为夸克物质,即强子-夸克相变。这种相变过程对于中子星的性质有着重要影响。考虑库仑能和表面能的影响,即有限尺度效应,相变过程中的混杂相包含了被称为pasta相的几何结构。强子-夸克共存相的平衡条件是通过求总能量的最小值得到的。采用相对论平均场（RMF）模型来描述强子物质相,采用Nambu-Jona-Lasinio（NJL）模型来描述夸克物质相。有限尺度效应一定程度上增加了中子星的最大质量,增加幅度取决于强子-夸克表面张力的大小。有限尺度效应能够降低混杂相的范围,其结果介于Gibbs结构和Maxwell结构的结果之间。研究结果表明,中子星中可能包含一个混杂相的核心部分,其大小受到表面张力等参数的影响。It is generally considered that hadron matter may undergo a deconfinement phase transition becoming quark matter at very high density in massive neutron stars. This hadron-quark phase transition has important impact on neutron stars, which has received much attention. We consider finite-size effect in this phase transition process, which contains the impact of Coulomb energy and surface energy. By including this effect, the mixed phase forms the pasta structures. The equilibrium conditions for coexisting hadronic and quark phases are derived by minimizing the total energy including the surface and Coulomb contributions. We employ the relativistic mean-field(RMF) model to describe the hadronic phase, while the Nambu-Jona-Lasinio(NJL) model is used for the quark phase. We conclude that the finite-size effect will raise the stiffness of EOS, and then increase the maximum mass of neutron stars, which depend on the value of surface tension. Our results show that finite-size effects can significantly reduce the region of the mixed phase, and the results lie between those from the Gibbs and Maxwell constructions. We show that a massive star may contain a mixed phase core and its size depends on the surface tension of the hadron-quark interface.     

胶子有效质量对重夸克势的影响

本文采用椭球袋模型讨论胶子有效质量对重夸克势的影响.我们分别计算了胶子有效质量0,0.2,0.4,0.6和1.0GeV时的重夸克势.计算结果表明,除汤川势外,势仍近似地呈线性,随着胶子有效质量的增加,斜率逐渐减小.     

重夸克偶素质量谱的相对论夸克模型研究（已撤稿）

使用量子场论中准势途径的相对论夸克模型,计算了重夸克偶素的质量谱.所采用的同味正反夸克间的有效相互作用包括通常的直接单胶子交换、单胶子湮没及具有相对论修正的标量和矢量线性禁闭的混合.得到了与实验上肯定的数据符合较好的拟合计算结果，并讨论了湮没项和相对论修正各项对能谱超精细分裂的作用. 关键词： 重夸克偶素 质量谱 相对论修正 湮没势     

夸克─夸克等效相互作用与手征对称性

从手征变换不变的要求出发给出了一个包括四种场交换的夸克－夸克等效相互作用势．用处理集团模型的共振群方法计算了核子－核子散射３Ｓ１和１Ｓ０态的相移．较好地解释了以往夸克势模型计算中１Ｓ０态相移与实验之间的差距．     

夸克─夸克等效相互作用与手征对称性

从手征变换不变的要求出发给出了一个包括四种场交换的夸克-夸克等效相互作用势.用处理集团模型的共振群方法计算了核子-核子散射³S₁和¹S₀态的相移.较好地解释了以往夸克势模型计算中¹S₀态相移与实验之间的差距.     

顶超对称夸克与重夸克的束缚态质谱

基于实验尚未完全排除最轻的超对称夸克伴子--标量顶夸克1(1)的寿命可相当长,以至在它产生后衰变之前有机会与通常夸克或胶子形成‘强子'的可能性的这一事实,建立了这一标量顶夸克1(1)和另一重夸克Q()组成的颜色单态束缚态(c1)和(b1)(以及它们反粒子相应的束缚态)的贝特-沙皮特方程,并借助瞬时近似求出了相应束缚态的质谱.     

Heavy Hadron Spectra to the Order 1/M in Heavy Quark Effective Theory

The heavy meson and baryon spectra are studied to the order of 1/M_Q in heavy quark effective theory. A phenomenological formula for the dependence of the spectra on the isospin and strangeness of the light quark system contained in heavy hadrons is proposed and its predictions are in agreement with the present experimental data. The predictions of beauty hadron masses including the 1/M_Q corrections are given. The parameters of the order of 1/M_Q are estimated from phenomenological analyses.     

Cornwall-Jackiw-Tomboulis Effective Potential for Quark Propagator in Real-Time Thermal Field Theory and Landau Gauge

We complete the derivation of the Cornwall-Jackiw-Tomboulis effective potential for quark propagator at finite temperature and finite quark chemical potential in the real-time formalism of thermal field theory and in Landau gauge. In the approximation that the function A(p2) in inverse quark propagator is replaced by unity, by means of the running gauge coupling and the quark mass function invariant under the renormalization group in zero temperature Quantum Chromadynamics (QCD), we obtain a calculable expression for the thermal effective potential, which will be a useful means to research chiral phase transition in QCD in the real-time formalism.     

Cornwall-Jackiw-Tomboulis Effective Potential for Quark Propagator in Real-Time Thermal Field Theory and Landau Gauge

We complete the derivation of the Cornwall-Jackiw-Tomboulis effective potentiM for quark propagator at finite temperature and finite quark chemical potential in the real-time formalism of thermal field theory and in Landau gauge. In the approximation that the function A（p^2） in inverse quark propagator is replaced by unity, by means of the running gauge coupling and the quark mass function invariant under the renormalization group in zero temperature Quantum Chromadynamics （QCD）, we obtain a calculable expression for the thermal effective potential, which will be a useful means to research chiral phase transition in QCD in the real-time formalism.     

Study of Top Quark FCNC

We study the one-loop contribution of the effective flavor changing neutral couplings （FCNC） tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.     

Study of Top Quark FCNC

We study the one-loop contribution of the effective flavor changing neutral couplings (FCNC) tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.     

相对论重离子碰撞与夸克物质

介绍了相对论重离子碰撞与夸克物质研究领域的有关最新进展.讨论了QCD热力学与量子输运理论,对于与QCD相变紧密联系的几个热点问题作了评述,最后分析了该研究领域在近期发展前景.     

The 1/Nc Expansion in Hadron Effective Field Theory

We study the N_c scalings of pion-nucleon and nucleon-nucleon scatterings in hadron effective field theory. By assuming Witten's counting rules are applied to matrix elements or scattering amplitudes, which use the relativistic normalization for the nucleons, we find that the nucleon axial coupling g_A is of order N_c0, and a consistent large N_c counting can be established for the pion-nucleon and nucleon-nucleon scatterings. We also justify the nonperturbative treatment of the low energy nucleon-nucleon interaction with the large N_c analysis and find that the deuteron binding energy is of order 1=N_c.     

Gluon Propagator and Heavy Quark Potential in an Anisotropic QCD Plasma

The hard-loop resummed propagator in an anisotropic QCD plasma in general linear gauges are computed. We get the explicit expressions of the gluon propagator in covariant gauge, Coulomb gauge and temporal axial gauge. Considering one gluon exchange, the potential between heavy quarks is defined through the Fourier transform of the static propagator. We find that the potential exhibits angular dependence and that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment.     

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.