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Diquarks: condensation without bound states

J. C. R. Bloch·C. D. Roberts·S. M. Schmidt
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Abstract

We employ a bispinor gap equation to study superfluidity at nonzero chemical potential: mu .neq. 0, in two- and three-colour QCD. The two-colour theory, QC2D, is an excellent exemplar: the order of truncation of the quark-quark scattering kernel: K, has no qualitative impact, which allows a straightforward elucidation of the effects of mu when the coupling is strong. In rainbow-ladder truncation, diquark bound states appear in the spectrum of the three-colour theory, a defect that is eliminated by an improvement of K. The corrected gap equation describes a superfluid phase that is semi-quantitatively similar to that obtained using the rainbow truncation. A model study suggests that the width of the superfluid gap and the transition point in QC2D provide reliable quantitative estimates of those quantities in QCD.

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J. C. R. Bloch, C. D. Roberts, S. M. Schmidt. 1999-07-21. Diquarks: condensation without bound states. https://doi.org/10.1103/physrevc.60.065208

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