Chiral Symmetry Breaking at Nonzero Chemical Potential
  We consider chiral symmetry breaking at nonzero chemical potential and discuss the relation with the spectrum of the Dirac operator. We solve the so called Silver Blaze Problem that the chiral condensate at zero temperature does not depend on the chemical potential while this is not the case for the Dirac spectrum and the weight of the partition function. 
J.C. Osborn, K. Splittorff and J.J.M. Verbaarschot