Singular values of the Dirac operator in dense QCD-like theories

Understand

We study the singular values of the Dirac operator in dense QCD-like theories at zero temperature.

• The Dirac singular values are real and nonnegative at any nonzero quark density.
• The scale of their spectrum is set by the diquark condensate, in contrast to the complex Dirac eigenvalues whose scale is set by the chiral condensate at low density and by the BCS gap at high density.
• We identify three different low-energy effective theories with diquark sources applicable at low, intermediate, and high density, together with their overlapping domains of validity.