“…(2,4) R (0, 0; q 1 , −q 1 , q 2 , −q 2 ; u, w) with four insertions φ 2 (q 1 ), φ 2 (−q 1 ), φ 2 (q 2 ), φ 2 (−q 2 ). The resulting expansion is too cumbersome to be presented here and will be given elsewhere [16]. Performing the derivatives with respect to the components of the vectors q 1 , q 2 we find:…”