Flavour asymmetry of anti-quarks in nuclei

A novel nuclear effect on the flavour asymmetry of anti-quarks in the nucleon bound in a nucleus is discussed in terms of the meson cloud model and the Pauli exclusion principle. It is expected that the flavour asymmetry is enhanced in a nucleus.Comment: 3 pages, Euro. Phys. J. A in pres

The quark-meson coupling model and chiral symmetry

We extend the quark-meson coupling (QMC) model to incorporate chiral symmetry. The relationship between the QMC model and chiral perturbation theory is also discussed. The nuclear central potential is modified by the effect of internal structure of nucleon.Comment: 6 pages, 1 figure, Contribution to the proceedings of "Achievements and New Directions in Subatomic Physics: Workshop in Honour of Tony Thomas' 60th Birthday," Special Centre for the Subatomic Structure of Matter, Adelaide, South Australia, February 15 - February 19, 2010

Relationship between Quark-Meson Coupling Model and Quantum Hadrodynamics

Using the quark-meson coupling (QMC) model, we study nuclear matter from the point of view of quark degrees of freedom. Performing a re-definition of the scalar field in matter, we transform QMC to a QHD-type model with a non-linear scalar potential. The potentials obtained from QMC are compared with those of the relativistic mean-field models.Comment: 6 pages, including 2 figs., to be published in Prog. Theor. Phys. (Kyoto) vol.108, no.

Quark-meson coupling model with short-range quark-quark interactions

Short-range quark-quark correlations are introduced into the quark-meson coupling (QMC) model phenomenologically. We study the effect of the correlations on the structure of the nucleon in dense nuclear matter. With the addition of correlations, the saturation curve for symmetric nuclear matter is much improved at high density.Comment: 6 pages (including 4 figures), to be published in Prog. Theor. Phys. (Kyoto) vol.105, no.2 (2001

Hyperons in neutron stars

Using the Dirac-Brueckner-Hartree-Fock approach, the properties of neutron-star matter including hyperons are investigated. In the calculation, we consider both time and space components of the vector self-energies of baryons as well as the scalar ones. Furthermore, the effect of negative-energy states of baryons is partly taken into account. We obtain the maximum neutron-star mass of $2.08\,M_{\odot}$, which is consistent with the recently observed, massive neutron stars. We discuss a universal, repulsive three-body force for hyperons in matter.Comment: 13 pages, 3 figures, 2 tables. arXiv admin note: text overlap with arXiv:1410.716

Equation of State for Neutron Stars in the Quark-Meson Coupling Model with the Cloudy Bag

Using the quark-meson coupling model with the cloudy bag, we construct the equation of state for neutron stars with hyperons in SU(3) flavor symmetry. The hyperfine interaction due to the gluon exchange and the pion-cloud effect inside a baryon is taken into account in vacuum and nuclear matter. We investigate how the quark degrees of freedom and the exchanges of gluon and pion between two quarks affect the properties of nuclear and neutron-star matter. It is found that the variation of baryon substructure in matter plays an important role in supporting massive neutron stars.Comment: 4 papes, 3 figures, 2 tables, accepted to the proceedings of the 8th International Conference on Quarks and Nuclear Physics (QNP2018) in JPS Conference Proceeding