Equation Icon  ⟨ ¯ ⟩ 2e- 2- 1- ¯tail Fa0 = − 3saa + 3 e˙aa + 3eRa0 + F a0 + O (s), (18.26 ) ⟨ ¯ ⟩ ¯ tail Fab = Fab + O(s). (18.27 )