Variational treatment of a π0-condensed state of high-density neutron matter

The stability of the standard ground state of pure neutron matter against a nonuniform spin-ordered state, yielding a nonvanishing expectation value of the π0 field, has been studied within the framework of the Jastrow variational approach. The results indicate that a first-order transition to the π0 condensate occurs at a density larger than normal nuclear density by a factor 3-4, provided a Δ-mixing of about 10% is included into the neutron states. (orig.)