Abstract: In the theoretical framework of the relativistic mean field, nuclear matter including delta isobars is studied. An analysis shows that with the increase of the relative delta isobar density the binding energy at saturation point goes down and moves toward the direction of the increase in density, then the equation of state becomes soft. We proposed that the neutron star matter including delta isobars may be possible phase structure for neutron stars.

Key words: relativistic mean field, delta isobar, equation of state