['In', 'the', 'mean', 'field', 'approximation', ',', 'the', 'Dirac', 'equation', 'for', 'the', 'quark', 'in', 'infinite', 'quark', 'matter', 'is', 'written', 'as', ':', '(', '30)iγ·∂−m−Vqs−γ0VqvψQMq(x)=0', '.']