Properties Of Neutron-rich Matter Research Articles

Fine tuning in an effective field based relativistic mean field model, and properties of neutron-rich matter

Properties of symmetric nuclear matter and neutron-rich matter predicted by effective field based relativistic mean field parameter sets are compared to those presented in a recent analysis of nuclear giant monopole resonance and isospin diffusion data and a study of the neutron skin of finite nuclei, as well as some selected observational data of neutron stars. Motivated by the fact that none of the published parameter sets of this model is simultaneously consistent with all previously mentioned constraints, an improvement not only in the isovector sector but also in isoscalar sector of this model is proposed. The properties of symmetric nuclear matter and neutron-rich matter, as well as some basic properties of static neutron stars predicted by the proposed parameter set (G2**), are discussed.

Isospin dependence of mechanical and chemical instabilities in neutron-rich matter

The rapid advance in experiments with rare isotopes has opened up several new frontiers in nuclear science @1#. The planned Rare Isotope Accelerator ~RIA! will further enhance the exploration of these forefronts dramatically @2#. Besides detailed information on the structure of exotic nuclei in many unexplored regions of the periodic chart, it is now possible to study novel properties of isospin-asymmetric nuclear matter with extreme neutron to proton ratios. Prospects for discovering new physics in warm neutron-rich matter of various densities that can be created transiently in nuclear reactions induced by exotic neutron-rich nuclei have generated much interest in the nuclear science community @3‐9#. In particular, the density dependence of the symmetry term in the equation of state ~EOS! has recently received much attention since it is among the most important but very poorly known properties of neutron-rich matter @10‐15#. This term is very important to the mechanisms of type II supernova explosions and neutron-star mergers. It also determines the proton fraction and electron chemical potential in neutron stars at b equilibrium. These quantities consequently influence the cooling rate of protoneutron stars and the possibility of kaon condensation in dense stellar matter @16 ‐20#. Based on the EOS obtained from various microscopic many-body theories and phenomenological models @21‐26#, it has long been predicted that isospin-asymmetric nuclear matter under certain conditions can be mechanically or chemically unstable, i.e.,