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

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