Calculations of Pion Excess in Nuclei

The authors construct, in the static potential approximation, the number operator for excess pions present in nuclei due to the pion-exchange forces between nucleons. Expectation values are calculated with use of variational wave functions obtained from a realistic Hamiltonian. Results are presented for systems ranging from the deuteron to nuclear matter: For example ⁵⁶Fe is estimated to have {~}7 extra pions, over and above the pion clouds associated with the individual nucleons.