Quantum fluctuation effects due to baryon resonances in nuclear mean field theory

We discuss the so-called vacuum fluctuation effects caused by many baryon resonances in the nuclear and neutron matter based on a relativistic Hartree theory. The obtained coupling parameters readjusted to reproduce the bulk properties of the nuclear matter are considerably smaller than those of the standard mean-field theory. As the result these effects soften the equation of state and the calculated incompressibility is close to the experimental one. We apply this model to the neutron matter and calculate the neutron star mass. (author)