Search

In the framework of a chiral constituent quark model, considering the contributions of $\pi$ annihilation and one-gluon annihilation, the proton-antiproton $S$-wave elastic scattering cross section experimental data can be reproduced by adjusting properly one-gluon annihilation coupling constant. Meanwhile, using the fixed model parameter, we do a dynamical calculation for all possible $S$-wave nucleon-antinucleon states, the results show that, there is no $S$-wave bound state as indicated by a strong enhancement at threshold of $p\bar{p}$ in $J/\psi$ and $B$ decays.

The symmetric spin–orbit interactions of one-gluon-exchange and confinement are included in the nucleon—nucleon phase shift calculation in the framework of quark delocalization colour screening model. The spin–orbit interaction has little influence on D wave phase shift. For the triplet P waves, 3PT is in good agreement with the experimental data and 3PLS is attractive but not strong enough, whereas 3PC is too strongly repulsive. Our results indicate that the symmetric spin–orbit interaction of one-gluon-exchange and confinement potential cannot give a good description of the triplet P wave phase shifts. More sophisticated considerations, the delocalization depending on the relative orientation between two cluster, might be needed to improve the description of P-wave NN interaction.

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.

We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the $N\bar{N}$ in $S$-wave (the quarks in the nucleons $N$ and $\bar{N}$, and the two nucleons relatively as well, are in $S$ wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of $p\bar{p}$ in $J/\psi$ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight $S$-wave bound state of six quarks, then the quantum number of the bound state is very likely to be $I=1, J^{PC}=0^{-+}$., Comment: 8 pages, 9 figures

The gluon and Goldstone boson induced tensor interaction effect on the dibaryon mass and the D-wavedecay width has been studied in the quark delocalization, color screening model. The effective S-D wave transition interactions induced by gluon and Goldstone boson exchanges decrease quickly as the increasing of the channel strangeness. The K and eta meson tenser contribution is negligible in this model. No six-quark state in the light flavor world can become a bound one by the help of these tensor interactions except the deuteron. The partial D-wave decay width of IJ(P) = (1)(/2) 2(divided by) NOmega state to spin 0,1 DeltaXi final state is 20.7 keV and 63.1 keV respectively. It is a very narrow dibaryon resonance and might be detected in the relativistic heavy ion reaction by the existing RHIC detectors through the reconstruction of the DeltaXi vertex mass and the future COMPAS detector at CERN and FAIR project in Germany.

The reaction p d -> d phi p_{sp} is studied within the Bethe-Salpeter formalism. Under special kinematical conditions (slow backward spectator proton p_{sp} and fast forward deuteron) relevant for forthcoming experiments at COSY, the cross section and a set of polarization observables factorize in the contribution of the pure subprocess p n -> d phi and a contribution stemming from deuteron quantities and kinematical factors. This provides a theoretical basis for studying threshold-near processes at quasi-free neutrons.

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

Resonating-group method has been applied to calculate the dibaryon state in the framework of the extended quark-delocalization color-screening model. The mass of the di-Ω is predicted to be about 45 MeV lower than the threshold. The effect of channel coupling due to the tensor force and sensitivity to meson exchange short-range cutoff radius, have also been studied.

The adiabatic effective baryon-baryon 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.

For a two-particle system in 3 ⊗ 3 Hilbert space, we derive a new type of inequality for local hidden variable model. Using an entangled state, we give a realizable experiment whose joint probabilities violate the inequality.

An inequality is deduced from local realism and a supplementary assumption. This inequality defines an experiment that can be actually performed with the present technology to test local hidden-variable models, and it is violated by quantum mechanics with a factor 1.92, while it can be simplified into a form where just two measurements are required.

Using the Akaishi—Yannazaki (AY) and Hyodo—Weise (HW) effective K, N, and KN interactions, we study possible existence of KN and N molecule states with I = 1/2,3/2 and JP = 1/2+ by means of three-body Faddeev equations. We find that for HW potential, KN and N systems with I = 1/2 both are bound hadron molecular states with about 10 MeV binding energy. The relativistic effects of kinetic energy are of the order of 4–5 MeV. AY potential would give larger binding energy because of overestimating N interaction strength. Although there are attractive interactions in the case of I = 3/2, the interaction is too weak to bind the systems.

In the frame of the constituent quark model with screened color confinement, non-strange baryon spectra are studied by using non-relativistic and semi-relativistic Faddeev equations in momentum space. The results show that a qualitative description of the high-energy baryon spectra can be obtained, especially for states at excitation energies from 1 to 1.5 GeV. Compared with the linear confinement potential, the discrepancy between non-relativistic and semi-relativistic approaches becomes smaller in the present model with screened color confinement.

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 10 MeV). The most favourable hidden colour channel of the H particle is given.