Meson-exchange corrections to the nuclear weak axial charge density in the hard pion model and 0 + 3 0 − transitions in A = 16 nuclei

Abstract

Starting with the hard-pion model based on a minimal chiral invariant phenomenological lagrangian, the two-body part of the time component of the weak axial-vector current is constructed in the tree approximation. Pion, rho- and A 1-meson exchanges are considered. The mesonic exchange operator obtained is applied to describe the purely weak axial 0 +↔0 −, ΔT = 1 transition in the nuclear A = 16 system. In order to treat nuclear structure correlation effects, explicit use of shell-model wave functions with configuration mixing is made. We confirm the large enhancement of the nuclear weak axial charge density with respect to impulse approximation.