Name: Ula (email_not_shown)
Date: 05/17/17-11:02:45 AM Z

Dear FeynCalc users,

In ``official" FeynCalc examples the identity matrix is not used under the trace. However, it seems that sometimes this yields wrong results when chiral projectors are present. Is this an expected bahavior, or I am doing something wrong? (I'm using FeynCalc 9.2.0 with Mathematica 8.0.4.)


In[2]:= ID = GA[6] + GA[7];
In[3]:= y1 = L1 GA[7] + R1 GA[6];
In[4]:= y2 = L2 GA[7] + R2 GA[6];

(*Worng result*)

In[5]:= Tr[y1.(GS[p2] + m2).y2.(GS[p1] - m1)] // FCE
Out[5]= -2 (L2 R1 + L1 R2) (m1 m2 - SP[p1, p2])
(*Correct result*)

In[6]:= Tr[y1.(m2).y2.(-m1)]
Out[6]= -2 m1 m2 (L1 L2 + R1 R2)

(*Correct result*)

In[7]:= Tr[y1.(GS[p2] + m2 ID).y2.(GS[p1] - m1 ID)] // Simplify // FCE
Out[7]= -2 m1 m2 (L1 L2 + R1 R2) + 2 (L2 R1 + L1 R2) SP[p1, p2]

Thanks and best wishes,

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