P^2 = 
s⋅t⋅u
─────
  4  
 
epsilon(zeta_3,2,3,4) = |delta| * (
               2          
s⋅s₃₄⋅t   s₁₄⋅t    s₂₄⋅t⋅u
─────── - ────── + ───────
   8        8         8   
) 
 
Sum_{cuts} 2*(s_34 epsilon(123,l3)-s_12 epsilon(l3,234))/(p4.l3) = Numerator/Denominator
 
Denominator = (p4.kappa3)^2 - (p4.zeta3))^2
 
Numerator = 
          2                                  
2⋅ε₁₂₃₄⋅lₜ ⋅(s⋅s₃₄ - s₁₄⋅t + u⋅(s₂₄ + 2⋅s₃₄))
─────────────────────────────────────────────
                      u                      
 
Numerator/(p4.kappa3) = 
          2
8⋅ε₁₂₃₄⋅lₜ 
