1/N expansion Eguchi–Kawai model O(N) vector models QCD in loop space fermions on a lattice finite temperatures gauge fields on a lattice instantons lattice gauge theories lattice methods matrix models multicolor QCD non-commutative gauge theories operator calculus path Integrals quantum anomalies reduced models second quantization thema EDItEUR::P Mathematics and Science::PH Physics::PHN Nuclear physics twisted reduced models