We investigate nucleon mass splitting at finite isospin chemical potential in the frame of two flavor Nambu--Jona-Lasinio model. It is analytically proved that, in the phase with explicit isospin symmetry breaking the proton mass decreases and the neutron mass increases linearly in the isospin chemical potential.
@article{arxiv.nucl-th/0702032,
title = {Nucleon Mass Splitting at Finite Isospin Chemical Potential},
author = {Sheng Chang and Jifeng Liu and Pengfei Zhuang},
journal= {arXiv preprint arXiv:nucl-th/0702032},
year = {2008}
}