Nuclear Matrix Elements of Axial-Charge Exchange Currents Derived in   Heavy-Fermion Chiral Perturbation Theory
  We calculate shell-model matrix elements of the axial-charge exchange current operators that have been obtained up to the next-to-leading order from heavy-fermion chiral perturbation theory. It is found that loop corrections to the soft one-pion-exchange contribution are small (around 10 \%) and have no significant dependence on the nuclear mass number or on the valence-nucleon orbits. These results render further support to the chiral-filtering conjecture. 
Tae-Sun Park, Ian S. Towner and Kuniharu Kubodera