  The self-consistent Green's functions method is employed to study the
spectroscopic factors of quasiparticle states around 16O, 28O, 40Ca and 60Ca.
The Faddeev random phase approximation (FRPA) is used to account for the
coupling of particles with collective excitation modes. Results for 16O are
reviewed first. The same approach is applied to isotopes with large
proton-neutron asymmetry to estimate its effect on spectroscopic factors. The
results, based on the chiral N3LO force, exhibit an asymmetry dependence
similar to that observed in heavy-ion knockout experiments but weaker in
magnitude.
