Using relativistic spin-flavor wave functions of a Lorentz-covariant light cone quark model, we calculate the electromagnetic form factors of two S11 resonances, N（1535） and N（1650）, and the helicity amplitudes A1...Using relativistic spin-flavor wave functions of a Lorentz-covariant light cone quark model, we calculate the electromagnetic form factors of two S11 resonances, N（1535） and N（1650）, and the helicity amplitudes A1/2 and S1/2 for electroexcitation of the S11 resonances from the nucleon. The electromagnetic form factors of these S11 resonances are found to be similar to those of the nucleon in shape, while the charge form factor of neutral N（1650） is nearly zero. The relative peak height of the S11 charge form factors is controlled by the mixing angle common to both resonance wave functions. As in most quark models, there is a systematic overestimate of A1/2 in both N（1535） and N（1650） cases at the photon point. A sizeable S1/2 for all cases is produced as suggested by experiments.展开更多
By means of a formal expression of Cornwall-Jackiw-Tomboulis effective potential for quark propagator at finite temperatures and finite quark chemical potentials, we derive the real-time thermal Schwinger-Dyson equati...By means of a formal expression of Cornwall-Jackiw-Tomboulis effective potential for quark propagator at finite temperatures and finite quark chemical potentials, we derive the real-time thermal Schwinger-Dyson equation for quark propagator in Landau gauge. Denote the inverse quark propagator by A（p^2）ψ - B（p^2）, we argue that, when temperature T is lower than the given infrared momentum cutoff pc, A（p^2） = 1 is a feasible approximation and can be assumed in discussions of chiral symmetry phase transition problem in QCD.展开更多
Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the co...Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.展开更多
Using the chiral symmetry spontaneous breaking Lagrangian with mean-field approximation, we investigate the in-medium quark condensate . It is found that the condensate decreases as the nuclear matter density increas...Using the chiral symmetry spontaneous breaking Lagrangian with mean-field approximation, we investigate the in-medium quark condensate . It is found that the condensate decreases as the nuclear matter density increases. Meanwhile, the desent deviates from the linear decrease and becomes remarkably slow as the density of the nuclear matter further increases. It shows that the chiral symmetry spontaneous breaking is only partially restored in densed nuclear matter.展开更多
By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-...By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.展开更多
In the framework of the littlest Higgs model with T-parity （LHT）, we study the top quark spin correlation and polarization at the International Linear Collider （ILC）. We find that the top quark polarization asymme...In the framework of the littlest Higgs model with T-parity （LHT）, we study the top quark spin correlation and polarization at the International Linear Collider （ILC）. We find that the top quark polarization asymmetry δPt and the left-right asymmetry δALR can respectively reach -35% and -37.5% for s = 500 GeV and s = 1000 GeV via e＋e- collision, which can reach the observable level at the ILC. By contrast, the spin correlation δC is smaller. The correlation behaviors of these observables at the e＋e- collision and the yy, collision will be helpful to distinguish different models and test the LHT model at the ILC.展开更多
The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluonexchange interactions is studied in a fully self-consistent method.The charge and parameter depe...The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluonexchange interactions is studied in a fully self-consistent method.The charge and parameter dependence of the stability of strangelets are discussed.It is found that the one-gluon-exchange interaction lowers the energy of a strangelet,and consequently allows the strangelet to be absolutely stable.The stable strangelet radius in the present model is smaller in comparison with the absence of one-gluon-exchange interaction,and can thus be much less than that of a normal nucleus with the same baryon number,according to the strength of the confinement and one-gluon-exchange interactions.展开更多
In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values...In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mz, 〈 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mz, approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s = 500 Ge V, 800 Ge V, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.展开更多
In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansi...In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value M_X =(5.57 ± 0.12) Ge V, which is consistent with the experimental data. The present prediction favors assigning the X(5568) to be the scalar tetraquark state.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10075056 and 90103020 and the CAS Knowledge Innovation Project under Grant No. KC2-SW-N02.
文摘Using relativistic spin-flavor wave functions of a Lorentz-covariant light cone quark model, we calculate the electromagnetic form factors of two S11 resonances, N（1535） and N（1650）, and the helicity amplitudes A1/2 and S1/2 for electroexcitation of the S11 resonances from the nucleon. The electromagnetic form factors of these S11 resonances are found to be similar to those of the nucleon in shape, while the charge form factor of neutral N（1650） is nearly zero. The relative peak height of the S11 charge form factors is controlled by the mixing angle common to both resonance wave functions. As in most quark models, there is a systematic overestimate of A1/2 in both N（1535） and N（1650） cases at the photon point. A sizeable S1/2 for all cases is produced as suggested by experiments.
文摘By means of a formal expression of Cornwall-Jackiw-Tomboulis effective potential for quark propagator at finite temperatures and finite quark chemical potentials, we derive the real-time thermal Schwinger-Dyson equation for quark propagator in Landau gauge. Denote the inverse quark propagator by A（p^2）ψ - B（p^2）, we argue that, when temperature T is lower than the given infrared momentum cutoff pc, A（p^2） = 1 is a feasible approximation and can be assumed in discussions of chiral symmetry phase transition problem in QCD.
基金国家自然科学基金，Foundations of the Chinese Academy of Sciences (X-37)，the Chinese Ministry of Education (B-22)，中国科学院资助项目，the Chinese Academy of Sciences
文摘Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.
文摘Using the chiral symmetry spontaneous breaking Lagrangian with mean-field approximation, we investigate the in-medium quark condensate . It is found that the condensate decreases as the nuclear matter density increases. Meanwhile, the desent deviates from the linear decrease and becomes remarkably slow as the density of the nuclear matter further increases. It shows that the chiral symmetry spontaneous breaking is only partially restored in densed nuclear matter.
文摘By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.
文摘In the framework of the littlest Higgs model with T-parity （LHT）, we study the top quark spin correlation and polarization at the International Linear Collider （ILC）. We find that the top quark polarization asymmetry δPt and the left-right asymmetry δALR can respectively reach -35% and -37.5% for s = 500 GeV and s = 1000 GeV via e＋e- collision, which can reach the observable level at the ILC. By contrast, the spin correlation δC is smaller. The correlation behaviors of these observables at the e＋e- collision and the yy, collision will be helpful to distinguish different models and test the LHT model at the ILC.
基金supported by the National Natural Science Foundation of China(Grant Nos.11135011 and 11045006)by the Chinese Academy Sciences Key Project(Grant No.Y12A0A0012)
文摘The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluonexchange interactions is studied in a fully self-consistent method.The charge and parameter dependence of the stability of strangelets are discussed.It is found that the one-gluon-exchange interaction lowers the energy of a strangelet,and consequently allows the strangelet to be absolutely stable.The stable strangelet radius in the present model is smaller in comparison with the absence of one-gluon-exchange interaction,and can thus be much less than that of a normal nucleus with the same baryon number,according to the strength of the confinement and one-gluon-exchange interactions.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11005089 and 11105116
文摘In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mz, 〈 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mz, approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s = 500 Ge V, 800 Ge V, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.
基金Supported by National Natural Science Foundation under Grant No.11375063Natural Science Foundation of Hebei Province under Grant No.A2014502017
文摘In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value M_X =(5.57 ± 0.12) Ge V, which is consistent with the experimental data. The present prediction favors assigning the X(5568) to be the scalar tetraquark state.
