Equation Icon  m2 = − PAA ′P AA′ = − 1A αβ ¯Aα′β′H αα′H ββ′ = − 1A αβ ¯Aαβ, (7.10 ) 4 1 αβ2γδ μνρσ 2 m = 4det Aαβ = 3!𝜀 𝜀 A αμAβνA γρAδσ. (7.11 )