Non-perturbative couplings and color superconductivity

Quark matter at sufficiently high density exhibits color superconductivity, due to attractive gluonic interactions. At lower densities of order A(QCD) (3), it has been proposed that instanton generated vertices may play an imp ortant role in the Cooper pair formation. We study the renormalization grou p flow to the Fermi surface of the full set of couplings generated by gluon ic and instanton interactions. In earlier work we showed that if the gluoni c interactions dominate at the matching scale, their running determines the : scale of the Cooper pair formation Delta. Here we consider all possibilit ies, including the one in which the instanton interactions dominate all oth ers at the matching scale, In the latter case we find that a number of addi tional induced couplings (including the gluonic ones) reach their Landau po les almost simultaneously with the instanton vertex. presumably all contrib ute to the Cooper pair formation. The most important consequence of includi ng all the couplings is a large increase in the gap size Delta. (C) 1999 Pu blished by Elsevier Science B.V. All rights reserved.