Narrow Results

A two-component model is developed for the intermediate-range NN interaction based on a new mechanism with an intermediate symmetric six-quark bag "dressed" by σ and other fields. To calculate the transition amplitude, the microscopic six-quark shell-model in combination with the ³P₀-quark pion production mechanism is used. As a result, an effective energy-dependent NN interaction is constructed. The new quark–meson model for the NN interaction has been demonstrated to result in a new type of NN tensor force at intermediate ranges, which is crucially important for the treatment of tensor mixing at intermediate energies. The suggested model is able to describe NN phase shifts in a broad energy range from low energy up to 1 GeV, and the deuteron structure. The generalization of the model results in new spin-orbit 2N and 3N forces and new meson-exchange currents induced by intermediate dressed bag components, and also in the enhancement of a collective σ-field in nuclei.

The Breit interaction contains terms that are singular in nature and cannot be used non-perturbatively for quark–antiquark bound state studies. We regularize the Breit interaction by subtraction such that the interaction is not singular at the origin but the intermediate and long-range parts of the interaction remain unchanged. With the regularized quark–antiquark potential and the confining potential, the solution of bound states are therefore stable possessing wave functions that can be used for future applications in other study of scattering and reaction problems.

We review the theoretical and experimental current status of the H dibaryon. We revise the recent experimental results obtained from double-Λ hypernuclei produced by means of Ξ-capture reactions using different target nuclei. Forthcoming experimental projects are briefly summarized. We also review the recent theoretical quark-model studies, some of them constrained by observables of the strangeness -2 two-baryon sector. Ongoing theoretical efforts by means of lattice QCD are also discussed.

The quark–meson coupling (QMC) model due to Guichon is formulated on the basis of the independent quark model of the nucleon proposed by Bogoliubov and is applied to the phenomenological descriptions of symmetric and asymmetric nuclear matter. For symmetric matter, the model predicts, at saturation density, the incompressibility $K=335.17$MeV, the quark effective mass $m_q^{\ast }=238.5$MeV and the effective nucleon mass $M^{\ast }=0.76M$, where $M$ is the nucleon mass in vacuum. Neutron star masses above two solar masses are obtained.

In this work, we calculate the mass spectrum of the bottom mesons with a modified nonrelativistic quark model by involving the screening effect, and explore their strong decay properties within the ³P₀ model. Our results suggest that the $B_1(5721)$, $B_2^{\ast }(5747)$, $B_J(5840)$ and $B_J(5970)$ could be reasonably assigned as the $B_1^{\prime }(1P)$, $B(1^3{P}_2)$, $B(2^1{S}_0)$ and $B(1^3{D}_3)$, respectively. The more precise measurements of the excited bottom mesons are crucial to confirm these assignments.