equation icon  integral 4 [ || 2|| ] H(x; m2) =_ ---1-- -d-p-eipx ln |p-|- ip signp0 h(- p2) 480p2 (2p)4 |m2| 1 integral d4p ( - (p0 + ie)2 + pip ) = -----2 lim ----4-eipx ln ---------2-------i . (110) 480p e-->0+ (2p) m