Spontaneous symmetry breaking and the energy of the nuclear isobaric analog state

O. CIVITARESE; F. MONTANI; M. REBOIRO

PHYS. REV. - C

AMER PHYSICAL SOC

Lugar: New York; Año: 2000 vol. 61 p. 64306 - 64310

0556-2813

The asymmetry between proton and neutron neumbers in a nucleus is viewed as a consequence of the spontaneous symmtry breaking of the isosping symmetry. The signatures of this effect, as it was suggested by Danchev, Khanna and Umezawa and co-workers, may have been already in the energetics of the nuclear isobaric analog resonance state and in the systematic of double-odd double-even mass differences. In order to account for finite size effects, not included in Umezawa´s approach, we have calculated the mean field term of  the Hamiltonian in a realistic nuclear single-particle basis. The nonvanishing value of the I3  current in the nonperturbative vacuum is explained in term of the ñ meson exchange.