Neutron-proton mass difference in finite nuclei and the Nolen-Schiffer   anomaly
  The neutron-proton mass difference in finite nuclei is studied in the framework of a medium-modified Skyrme model. The possible interplay between the effective nucleon mass in finite nuclei and the Nolen-Schiffer anomaly is discussed. In particular, we find that a correct description of the properties of mirror nuclei leads to a stringent restriction of possible modifications of the nucleon's effective mass in nuclei. 
Ulf-G. Mei{\ss}ner, A.M. Rakhimov, A. Wirzba, U.T. Yakhshiev