Kiro Miyazaki A resolution of Gordon ambiguity in nuclear current (127K, PDF) ABSTRACT. We investigate the electromagnetic vertex function of a nucleon in relativistic nuclear medium. In the corresponding Feynman diagram, the effect of mean-fields on the internal nucleon propagators connected to external ones offsets the difference between the familiar CC2 current and the so-called CC1 or CC3 current. It is therefore found that the CC2 current is physically reasonable. Consequently, the famous Gordon ambiguity of the nuclear current has been resolved.