Name: Rolf Mertig (email_not_shown)
Date: 03/26/01-11:48:43 PM Z


Hi,
there is nothing wrong with the answer. If you
apply the Schouten identity it's zero:

In[1]:= <<HighEnergyPhysics`fc`

FeynCalc4.1.0.3b Type ?FeynCalc for help or visit http://www.feyncalc.org
$PrePrint is set to FeynCalcForm. Use FI and FC to change the display
format.

In[2]:= x=GA[5].GS[t].GS[z];

In[3]:= a=Tr[DiracSlash[p,k,d,c].x]; b=Tr[x.DiracSlash[p,k,d,c]];

In[4]:= Length[Expand[a-b]]

Out[4]= 8

In[5]:= Schouten[a-b]

Out[5]= 0

In[6]:= Contract[a-b,Schouten->100]

Out[6]= 0

In[7]:= ?Schouten
Schouten[expr] applies the Schouten identity on at most 42 terms in a
sum. If
   Schouten should operate on larger expression you can give a second
   argument, e.g.: Schouten[expr, 4711] which will work on sums with less
   than 4711 terms.
 Schouten is also an option of Contract and DiracTrace. It may be set to
an
   integer indicating the maximum number of terms onto which the function
   Schouten will be applied .
------------------

Regards,

Rolf Mertig

On Fri, 23 Mar 2001, Sergey Cherkas wrote:
> Greetings,
> I type:
> x=GA[5].GS[t].GS[z]
>
> Tr[DiracSlash[p,k,d,c].x]
>
> Tr[x.DiracSlash[p,k,d,c]]
>
> Then, in surprise, I obtain two different answer.
> Please, help me to choose what answer is right.
>
> Best regards,
>
> Segrey Cherkas
>



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