Virtual Color Superconductivity and Nucleon Structure

The observed electromagnetic (EM) properties of a nucleon at high energy are studied to search for a possible metastable color superconducting phase, called a virtual phase, that has an energy density close to the true ground state of the vacuum. The discussion is based on a mechanism of spontaneous partial breaking of the EM U(1) gauge symmetry inside a color superconductor. Favorable evidences for such a scenario are found.