The onset of proton-neutron correlations in nuclei

Proton-neutron correlations in nuclei can be explained in part by isosclar and isovector pairing. Shell model techniques reveal additional strong proton-neutron correlations that were recently observed in neutron transfer reactions. I will discuss the pieces of the effective interaction that contribute to these strong correlations. I will also show the the observed $1^+0$ and $0+1$ low-lying states in odd-odd nuclei are geometrically favored in the two-body random ensemble model.