Equation of state of isospin-asymmetric nuclear matter in relativistic mean-field models with chiral limits

Using in-medium hadron properties according to the Brown-Rho scaling due to the chiral symmetry restoration at high densities and considering naturalness of the coupling constants, we have newly constructed several relativistic mean-field Lagrangians with chiral limits. The model parameters are adjusted such that the symmetric part of the resulting equation of state at supra-normal densities is consistent with that required by the collective flow data from high energy heavy-ion reactions, while the resulting density dependence of the symmetry energy at sub-saturation densities agrees with that extracted from the recent isospin diffusion data from intermediate energy heavy-ion reactions. The resulting equations of state have the special feature of being soft at intermediate densities but stiff at high densities naturally. With these constrained equations of state, it is found that the radius of a 1.4M(circle dot) canonical neutron star is in the range of 11.9 km <= R <= 13.1 km, and the maximum neutron star mass is around 2.0M(circle dot) close to the recent observations. (c) 2007 Elsevier B.V All rights reserved.