2005/12/31 by Krishna Rajagopal, Andreas Schmitt · 8 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #High-Energy Particle Collisions Research #High-pressure geophysics and materials #cond-mat.supr-con #hep-ph #nucl-th
paper · pdf · doi:10.1103/physrevd.73.045003
published as Phys.Rev.D73:045003,2006 · 20 pages, 4 figures; v2: some modifications in Appendix B; references added; version to appear in Phys. Rev. D
arxiv created 2006/01/18 · openalex publication_date 2006/02/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
At sufficiently high densities, cold dense three-flavor quark matter is in the color-flavor locked (CFL) phase, in which all nine quarks pair in a particularly symmetric fashion. Once the heaviness of the strange quark (mass ms) and the requirements of electric and color neutrality are taken into account, the CFL pattern of color superconductivity requires the pairing of quarks that would, in the absence of pairing, have Fermi momenta that differ by of order ms2/\ensuremathμ, with \ensuremathμ the quark number chemical potential. This means that at sufficiently small \ensuremathμ, the ``stress'' on the pairing is large enough that the system can lower its energy by breaking pairs, resulting in some unconventional color superconductor which includes gapless excitations, spatial inhomogeneity, counter-propagating currents, or all three. In this paper we ask whether there is some less symmetric but still conventional pattern of pairing that can evade the stress. In other words, is there a pattern of pairing in which, once electric and color neutrality are imposed by suitable chemical potentials, pairing only occurs among those quarks whose Fermi momenta would be equal in the absence of pairing? We use graph-theoretical methods to classify 511 patterns of conventional color-superconducting pairing, and show that none of them meet this requirement. All feel a stress, and all can be expected to become unstable to gapless modes at a density comparable to that at which the CFL phase becomes unstable.