Chiral-particle Approach to Hadrons in an Extended Chiral (σ,π,ω) Mean-Field Model

The chiral nonlinear ($\sigma,\pi,\omega$) mean-field model is an extension of the conserving nonlinear (nonchiral) $\sigma$-$\omega$ hadronic mean-field model which is thermodynamically consistent, relativistic and Lorentz-covariant mean-field theory of hadrons. In the extended chiral ($\sigma,\pi,\omega$) mean-field model, all the masses of hadrons are produced by chiral symmetry breaking mechanism, which is different from other conventional chiral partner models. By comparing both nonchiral and chiral mean-field approximations, the effects of chiral symmetry breaking to the mass of $\sigma$-meson, coefficients of nonlinear interactions, coupling ratios of hyperons to nucleons and Fermi-liquid properties are investigated in nuclear matter, hyperonic matter, and neutron stars.