Subtraction of Spurious Centre-of-Mass Motion in Quark Delocalization and Colour Screening Model

The quark delocalization colour screening model provides an alternative approach for the NN intermediate range attraction, which is attributed to the σ meson exchange in the meson exchange and chiral quark model. However the quark delocalization induces the spurious centre-of-mass motion （CMM）. A method for subtracting the spurious CMM proposed before is applied to the new scattering calculation. The subtraction of the spurious CMM results in an additional NN attraction. The NN scattering data are refitted by a fine tune of the colour screening constant.     

Kaonic Nuclear Cluster Kpp in Quark Delocalization Colour Screening Model

The quark-delocalization colour-screening model is employed to study the kaonic nuclear cluster K-pp system. The calculation shows that there is a strong effective attraction between kaon and protons. The bound state can be formed and the binding energy is estimated to be about 80 MeV, and the space configuration is a symmetrical linear triatomic molecule with radius 1.15 fm. The results also show that the quark delocalization is responsible for the strong attraction in the system and the colour screening adds a little attraction in this case.     

Exploring High Strangeness Dibaryons with the Extended Quark Delocalization and Color Screening Model

Promising high strangeness dibaryons are studied by the extended quark delocalization and color screening model. It is shown that besides H particle and di-Ω, there might be other dibaryon candidates worth to be searched experimentally such as NΩ.     

夸克蜕定域、色屏蔽和核力的中程吸引

本文描述了在通常的夸克势模型中的夸克蜕定域、色屏蔽及核力特性,对所得核子—核子绝热近似势和散射相移进行了定性描述:既有排斥心,又有中程吸引,但没有Van der Waals力问题,变分给出蜕定域的数值也是合理的,对质心运动效应、色屏蔽形式的影响以及各种单夸克基矢的关系和选择问题进行了专门的研究。 We introduce the quark delocalization and color screening into the usual quark modeland the property of nuclear force. The resulting N-N phase shifts and the adiabatic potential aredescribed qualitatively well: there are exclusion core and also intermediate range attraction, but thereis no Van der Waals force. The delocalization parameter obtained from variational method is alsoreasonable. we consider especially the effect of mass center motion, the effect of forms of colorscreening...     

Pentaquark Masses and Magnetic Moments in a Quark Cluster Approach

We study the stability of the different quark substructures in a quark cluster approach to pentaquark states considering the color-magnetic spin-spin interactions between quarks. The most likely configuration is found to be a triquark-diquark one where the two clusters are in a relative p-wave, the two quarks of the diquark are coupled to spin zero and anti-triplet representations of flavor and color, and the triquark has spin ? and belongs to the triplet representation of color and to the anti-sextet of flavor. Using this configuration we estimate the masses and magnetic moments of pentaquarks. Finally the calculation of the masses has been extended to some charmed pentaquarks.     

Charmed Baryon in Diquark Model

A diquark model is used to investigate single-charmed baryons.In this model,baryon is composed of two diquarks and an antiquark.Masses of lowest lying states with J~P=1/2~(±) are obtained.Baryons in our results are as heavy as other theoretic predictions and we suggest that the five-quark components should be considered in any three-quark model for studying the charmed baryons.     

Effect of Hidden Colour Channel on H Particle in Chiral Quark Model

The structure of the H particle is studied in the framework of chiral quark model by solving the resonating group equation of coupled-channel. Four physical channels and eleven hidden colour channels are taken into account. Hidden colour channel coupling is found to cause an obvious decrease of eigenenergy of the H particle （about IO MeV）. The most favourable hidden colour channel of the H particle is given.     

包含轻子结构的夸克模型

对标准模型作手征性扩充后,模型中平行地存在手征性相反的夸克态.相应于构成强子的f代普通夸克,新加的同样代数、手征性相反的夸克可能构成轻子.对扩充后的模型超对称化之后,使得渐近自由性质的破坏所要求的代的数目从大于33/8减少到大于9/4,从而有可能解释手征相反的夸克构成的轻子为什么比普通夸克构成的强子大小要小得多等特点.     

Phase Structure in a Quark Mass Density-and-Temperature-Dependent Model

The phase diagram of bulk quark matter in equilibrium with a finite hadronic gas is studied. Different from previous investigations, we treat the quark phase with the quark mass density-and-temperature-dependent model to take the strong quark interaction into account, while the hadron phase is treated by hard core repulsion factor. It is found that the phase diagram in this model is, in several aspects, different from those in the conventional MIT bag model, especially at high temperature. The new phase diagram also has strong effects on the mass-radius relation of compact hybrid stars.     

Spin Structure of Baryons in Orbiting Valence Quark Model

The quark model with orbital motion of the valence quarks is constructed to reproduce the spin structure of baryons. The relations between the spin-averaged sum rules and baryon magnetic moments found in the previous works do not remain, unless the small orbital magnetic moments are neglected. In particular, when the orbital motion of the valence quarks leads to the small contribution of quark orbit-spin to baryon magnetic moments, the sum rules for polarized nucleon are in agreement with the recent experiment.     

Unquenching the Quark Model

The formalism for a new generation of unquenched quark models for baryons in which the effects of quark?Cantiquark pairs are taken into account in an explicit form via a microscopic, QCD-inspired, quark?Cantiquark creation mechanism, is presented. As an application the quark?Cantiquark contribution to the spin of the proton and the ??⁺ is discussed. Finally the strangeness radius of the ??⁺ in the closure limit is calculated.     

Sum Rules in the Quark Model

With the help of various sum rules we look into the spin-isospin excitations in nuclei within a framework of the quark model. The effect of Pauli correlations is explicitly taken care of. In agreement with the experiments we find negligible amount of M1 strength in heavy nuclei. This is explained in terms of the Fermi gas model.     

Tetraneutron in the Chiral Quark Model

The tetraneutron state is studied in the framework of the chiral quark model with tetrahedron configuration. The universal attraction property of σ-meson exchange leads to a strong attraction in the effective potential of the system. It is possible to form a bound state. For comparison, the naive quark model is also employed to carry out the calculation. A weak attraction, which is too weak to bind the system, is obtained.     

Mesons in the Constituent Quark Model

The quark-antiquark （q^-q） spectrum is studied by solving the Schrōdinger equation in the framework of nonrelativistic constituent quark model. An overall good fit to the experimental data of meson is obtained. The interactions between quark and antiquark consist of quadratic colour confinement-exchange, one-gluon-exchange, and Goldstone-boson-exchange potentials.     

Scalar Mesons in the Light-Front Quark Model

We discuss light-front quark-model calculations of the scalar meson spectrum and decays.     

Chiral Extension of the Quark Model

The chiral extension of the minimal standard model makes quarks with two chiralities present parallelly. Some interesting questions, such as the possibility of that the leptons are made of additional leptonic quarks and the proton decay are discussed.     

Diquark correlations in the proton

The colour-magnetic interaction of quantum chromodynamics with a smearing function found from the fit to the - splitting is strong enough to support a bound state of a singletqq pair. We examine the possibility that this interaction leads to short-range quark-quark correlations in light baryons there-by providing the dynamical mechanism for a quark-diquark picture of the proton. In particular, we show that the correlation function of a singlet diquark in the proton is strongly enhanced at the origin (compared to that for the triplet diquark) with the correlation radiusr ₀, a typical cut-off radius in the spin interaction. The Fourier transform of the correlation function, which is related to the dependence on the momentum transfer of the structure functions in inclusive electron-proton scattering, may provide quite fundamental information on the diquark structure of the proton.     

Mesons in the Quark Model of Superconductivity Type

On the basis of a quark model of superconductivity type, effective chiral Lagrangians are obtained for strong, electromagnetic and weak interactions of scalar, pseudoscalar, vector and axial vector meson nonets at low energies. The spontaneous breaking of chiral symmetry plays an important role. The form factors of strong and electromagnetic vertices, meson masses and different types of meson decaysare discussed.