Effects of three-nucleon forces and two-body currents on Gamow-Teller   strengths
  We optimize chiral interactions at next-to-next-to leading order to observables in two- and three-nucleon systems, and compute Gamow-Teller transitions in carbon-14, oxygen-22 and oxygen-24 using consistent two-body currents. We compute spectra of the daughter nuclei nitrogen-14, fluorine-22 and fluorine-24 via an isospin-breaking coupled-cluster technique, with several predictions. The two-body currents reduce the Ikeda sum rule, corresponding to a quenching factor q^2 ~ 0.84-0.92 of the axial-vector coupling. The half life of carbon-14 depends on the energy of the first excited 1+ state, the three-nucleon force, and the two-body current. 
A. Ekstr\"om, G. R. Jansen, K. A. Wendt, G. Hagen, T. Papenbrock, S.   Bacca, B. Carlsson, and D. Gazit
nucl-th nucl-ex