Equation Icon  ( ) ⟨ || μν || ⟩ ∫ dnk kμkν ημν m2 n∕2 ( n ) 0|Tˆn [η ]|0 = − i ----n--2-----2-----= ---- --- Γ − -- , (89 ) (2π) k + m − iε 2 4 π 2