L  [A(f1,f2,f3,f4,b5)] =

       + ss1^-1*ss3^-1 * (
          - chi(1)*ga(k5)*chi(2)*chi(3)*ga(e5)*chi(4)
          + chi(1)*ga(e5)*chi(2)*chi(3)*ga(k5)*chi(4)
          + chi(1)*ga(N1_?)*chi(2)*chi(3)*ga(N1_?)*chi(4)*k1.e5
          + chi(1)*ga(N1_?)*chi(2)*chi(3)*ga(N1_?)*chi(4)*k2.e5
          )

       + ss1^-1*ss4^-1 * (
          - chi(1)*ga(N1_?)*chi(2)*chi(3)*ga(N1_?)*chi(4)*k4.e5
          + 1/2*chi(1)*ga(N1_?)*chi(2)*chi(3)*ga(N1_?)*ga(e5)*ga(k5)*chi(4)
          )

       + ss2^-1*ss4^-1 * (
          + chi(1)*ga(N1_?)*chi(4)*chi(2)*ga(N1_?)*chi(3)*k4.e5
          - 1/2*chi(1)*ga(N1_?)*ga(e5)*ga(k5)*chi(4)*chi(2)*ga(N1_?)*chi(3)
          )

       + ss2^-1*ss5^-1 * (
          + chi(1)*ga(k5)*chi(4)*chi(2)*ga(e5)*chi(3)
          - chi(1)*ga(e5)*chi(4)*chi(2)*ga(k5)*chi(3)
          - chi(1)*ga(N1_?)*chi(4)*chi(2)*ga(N1_?)*chi(3)*k1.e5
          - 1/2*chi(1)*ga(N1_?)*ga(e5)*ga(k5)*chi(4)*chi(2)*ga(N1_?)*chi(3)
          )

       + ss3^-1*ss5^-1 * (
          - chi(1)*ga(k5)*chi(2)*chi(3)*ga(e5)*chi(4)
          + chi(1)*ga(e5)*chi(2)*chi(3)*ga(k5)*chi(4)
          + chi(1)*ga(N1_?)*chi(2)*chi(3)*ga(N1_?)*chi(4)*k1.e5
          + 1/2*chi(1)*ga(N1_?)*ga(e5)*ga(k5)*chi(2)*chi(3)*ga(N1_?)*chi(4)
          );