(* Created with the Wolfram Language for Students - Personal Use Only : www.wolfram.com *)
(-8*CF*(-1 + z4) + 
  (CA*(sP3*(-(s34^2*(-1 + z34)) + 8*sP4^2*z3*(-1 + z4) + 
       4*s34*sP4*(z3 - 2*z4)*(-1 + z4)) + 
     sP3^2*(s34 - s34*z34 - 8*sP4*(-1 + z4)*z4) + s34*sP4*(s34 + sP4)*
      (-1 + z4 + z3*(-3 + 4*z4))))/(s34^2*sP4*z34))/(8*sP3*(-1 + z34))
