The nonperturbative color Meissner effect in a two-flavor color superconductor

Color superconductivity in QCD breaks the SU(3) color gauge group down to SU(2), inducing masses in five of the eight gluons, This is a dynamical Higgs effect, in which the diquark condensate acts as the vacuum expectation value of a composite scalar field. In order to analyze this effect at low quark density, when gaps are large and generated nonperturbatively, we use instanton-induced quark interactions augmented with gauge-invariant interactions between quarks and perturbative gluons. The five gluon masses are found from the static limit of the relevant polarization operators, in which transversality is maintained via the Nambu-Goldstone modes of broken color symmetry. Working in the microscopic theory we calculate these masses to one-loop order and estimate their density dependence. Finally, we speculate that the Meissner effect may postpone the onset of color superconductivity to higher matter density than estimated previously. (C) 2000 Elsevier Science B.V. All rights reserved.