Equation Icon  [ (1) β (1) β ] tr V a Gmn V b Grs = ∫ ∫ dnk dnq ′ dnx dnx ′haμν(x)hbαβ(x ′) ------------eik(x−x ) &tidle;G βmn(k + q)G&tidle;βrs(q)T μν,αβ(q,k), (196 ) (2π )n(2π )n