Introduction to Color Superconductivity
  At high nuclear density and small temperature, due to the asymptotic freedom property of Quantum ChromoDynamics and to the existence of an attractive channel in the color interaction, diquark condensates might be formed. Since these condensates break the color gauge symmetry, this phenomenon has the name of color superconductivity. In the last few years this has become a very active field of research. While a direct experimental test is still missing, color superconductivity might have implications in astrophysics because for some compact stars, e.g. pulsars, the baryon densities necessary for color superconductivity can probably be reached. 
G. Nardulli