Equation Icon  ξa(τ ) = (τ, 0,0,iξ3) (5.45 ) u = X (τ, ζ, ¯ζ) = ξa(τ)ˆl(ζ,ζ¯) ≡ √τ-− iξ3Y 0 , B a 2 2 1,3 ¯ 3 1 L (uB,ζ, ζ) = iξIY 1,3, J i = Si = MBc ξ3δi3 = MBc (0,0,ξ3) = MBc ξiI.