Equation Icon  ∫ ′ μναβ ′ 4π- 2 -d4p--eip(x−-x)P-μναβ θ(−-p2) ℋ (x,x ) = 45 G (2π)4 || 2 2||2. (146 ) |1 + 4π Gp H&tidle;(p;μ¯ )|