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.     

洛伦兹规范条件下对单胶子夸克势的QCD非微扰修正形式

在洛伦兹规范条件下,导出了具有平移不变性的双胶子两点函数真空平均值.利用所获得的双胶子真空期待值,给出了对微扰单胶子交换夸克–夸克势、夸克–反夸克对湮没和夸克–反夸克对激发势的最低阶非微扰QCD修正形式.     

B稀有辐射衰变对似矢量夸克模型约束的研究

在似矢量夸克模型中, 具有一个为SU(2)单态的下夸克D以及树图b→sZ^*相互作用z_sb. 在此框架下,(1) 通过考察描述B→X_sγ的Wilson系数随重正化标度从m_D到弱标度的跑动, 研究了D夸克对此衰变的影响.(2) 使用最近对B→X_sl⁺l^－的测量,获得了对z_sb相当严格的限制. 发现前后不对称的零点值可以与标致模型的预言有大的偏离, 并对z_sb十分敏感, 可以用来探测新物理.     

单胶子交换梯形近似下Bethe－Salpeter方程赝标解

将在动量空间具有积分形式的单胶子交换梯形近似下Ｂｅｔｈｅ－Ｓａｌｐｅｔｅｒ方程化为微分方程，求出该方程在四动量为零时的赝标解全部分量，其中第一分量为已知的Ｇｏｌｄｓｔｅｉｎ解．     

对单胶子交换势的非微扰修正研究

对单胶子交换势的非微扰修正进行了系统研究,结果表明,要获得规范不变的修正形式,QCD真空胶子场必须取为协变规范.在协变规范下,给出了单胶子交换势的非微扰修正的新形式.     

The ■ tetraquark states and the structure of X(2239) observed by the BESⅢ collaboration

We investigate the mass spectrum of the■tetraquark states in the relativized quark model.By solving the Schrodinger-like equation with the relativized potential,the masses of S-and P-wave■tetraquarks are obtained.The screening effects are also taken into account.It is found that the resonant structureX(2239)observed in thee+e-→K+K-process by the BESIII collaboration can be assigned as a P-wave 1--■tetraquark state.Furthermore,the radiative transition and the strong decay behavior of this structure are also estimated,which can provide helpful information for future experimental searches.     

Two-body effects on baryon magnetic moments and radiative decays of mesons

We demonstrate that the two-body interaction effects involving spectator quark can account for the discrepancy between theory and experiment for the baryon magnetic moments and meson radiative decays.     

夸克喷注与胶子喷注角分布特性的研究

用蒙特卡洛模拟Jetset 7.4产生质心能量为91.2GeV的正负电子对撞事件. 在引入喷注的圆锥角后, 对不同味的夸克喷注和由不同味夸克发射的胶子产生的喷注的角分布特性进行了仔细研究. 结果发现, 在相同的能量下, 胶子喷注的角分布范围比夸克喷注的角分布范围要明显宽一些. 在带电粒子数、横动量相同的条件下, 胶子喷注的平均圆锥角比夸克喷注的平均圆锥角大很多. 喷注的平均圆锥角随带电多重数以及喷注的横动量的分布都呈线性正关联. 由不同味的夸克发射的胶子产生的喷注的圆锥角分布特性相同；而不同味的夸克喷注的圆锥角分布存在明显的差异.     

Properties of Charmonium States in a Phenomenological Approach

We investigate the spectrum and decay rates of charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining potential along with the potential derived from instanton vacuum to account for the hyperfine mass splitting of charmonium states in variational approach. We predict radiative E1, M1, two-photon, lepton and two-gluon decay rates of low lying charmonium states. An overall agreement is obtained with the experimental masses and decay widths.We have estimated the branching ratio of two gluons decaying into light hadrons.     

cb System: Mass Spectra and Decays

For the cb system, the mass spectra, decay constants, El and M1 transition rates are calculated in a QCD-inspired potential model. Relativistic corrections are taken into account. The El transition rates with relativistic corrections are found to be smaller than those obtained in other models.     

Heavy quarkonia spectra and their decays in a relativistic quark model

Using the phenomenological relativistic harmonic model (RHM) for quarks, we have obtained the masses of S wave charmonium and bottomonium states. The full Hamiltonian used in the investigation has Lorentz scalar plus vector confinement potential, along with the confined one gluon exchange potential (COGEP). A good agreement with the experimental masses for the ground and the radially excited states is obtained both for the triplet and singlet S wave mesons. The decay properties of the ground state charmonium and bottomonium are investigated.     

核子–核子散射过程的研究和矢量介子交换势

在推广的手征SU(3)夸克模型下讨论了核子–核子散射过程和矢量介子交换势.给出了赝标π介子和矢量ρ和ω介子的GCM中心力的交换势和NN散射14个分波的相移.研究表明,矢量介子交换势可以替代单胶子交换势以解释核力的短程排斥.     

夸克胶子喷注的人工神经网络识别研究

为了将人工神经网络用于高能物理中对喷注的分类识别,用从高能正负电子对撞的蒙特卡洛模拟中得到的不对称三喷注事件中的夸克喷注和胶子喷注的平均多重数、平均横动量和两类喷注所对的夹角的平均值作为输入BP神经网络的3个特征参量,对2?.5—2?2?.5GeV能区的8个能量间隔进行等精度的训练.用训练好的神经网络模型对不对称三喷注事件中的夸克喷注和胶子喷注样本进行检验判定,并对混合喷注样本进行分类识别.所得结果表明,有望将人工神经网络用于高能正负电子对撞产生的喷注的分类分析.     

Semileptonic decays of baryons in a relativistic quark model

We calculate semileptonic decays of light and heavy baryons in a relativistically covariant constituent quark model. The model is based on the Bethe-Salpeter equation in instantaneous approximation. It generates satisfactory mass spectra for mesons and baryons up to the highest observable energies. Without introducing additional free parameters we compute on this basis helicity amplitudes of electronic and muonic semileptonic decays of baryons. We thus obtain form factor ratios and decay rates in good agreement with experiment.     

无限深阱势的非线性谱生成代数与新型相干态

利用对称一维无限深阱势的哈密顿算符和自然算符构造出该势场的非线性谱生成代数,并在此基础上得到了一种新的非线性相干态.该相干态具有时间稳定性,既可以看成本征值为算符函数的降算符本征态,也可以看成广义极小测不准状态的转动态.     

Masses of S and P wave mesons and pseudoscalar decay constants using a confinement scheme

In the framework of relativistic harmonic confinement model for quarks and antiquarks, the masses of S- and P-wave mesons and pseudoscalar decay constants from light flavour to heavy flavour sectors are computed. The residual two-body Coulomb interaction and the spin-dependent interaction of the confined one gluon exchange effects (COGEP) such as spin-spin and spin-orbit interactions are perturbatively incorporated with the confinement energy to get the respective vector-pseudoscalar meson mass differences. Here we employ the same parametrization and model parameters as used in a recent study of low-lying hadron masses and leptonic decay widths. The results are being compared with the values obtained from other theoretical models and the experimental values.