QCD at finite baryon density: Nucleon droplets and color superconductivity

Mark Alford, Krishna Rajagopal, Frank Wilczek

Research output: Contribution to journalArticlepeer-review

1118 Scopus citations


We use a variational procedure to study finite density QCD in an approximation in which the interaction between quarks is modelled by that induced by instantons. We find that uniform states with conventional chiral symmetry breaking have negative pressure with respect to empty space at all but the lowest densities, and are therefore unstable. This is a precisely defined phenomenon which motivates the basic picture of hadrons assumed in the MIT bag model, with nucleons as droplets of chiral symmetry restored phase. At all densities high enough that the chirally symmetric phase fills space, we find that color symmetry is broken by the formation of a 〈qq〉 condensate of quark Cooper pairs. A plausible ordering scheme leads to a substantial gap in a Lorentz scalar channel involving quarks of two colors, and a much smaller gap in an axial vector channel involving quarks of the third color.

Original languageEnglish (US)
Pages (from-to)247-256
Number of pages10
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-4
StatePublished - Mar 12 1998
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'QCD at finite baryon density: Nucleon droplets and color superconductivity'. Together they form a unique fingerprint.

Cite this