Name: Dimitry Fedorov (email_not_shown)
Date: 05/15/08-08:55:04 AM Z

This code will work and gives needed result:

ma = DiracSimplify[
SpinorUBar[k1, m].DiracMatrix[mu].SpinorU[p1, m]] DiracSimplify[
SpinorUBar[k2, m].DiracMatrix[mu].SpinorU[p2, m]];
mac = ComplexConjugate[ma] /. {mu -> nu};
amps = Simplify[Contract[FermionSpinSum[ma mac] /. DiracTrace -> TR]]

or so:

ma1 = DiracSimplify[SpinorUBar[k1, m].DiracMatrix[mu].SpinorU[p1, m]]
ma2 = DiracSimplify[SpinorUBar[k2, m].DiracMatrix[mu].SpinorU[p2, m]]
mac1 = ComplexConjugate[ma1] /. {mu -> nu}
mac2 = ComplexConjugate[ma2] /. {mu -> nu}
amps1 = Simplify[FermionSpinSum[ma1 mac1] /. DiracTrace -> TR]
amps2 = Simplify[FermionSpinSum[ma2 mac2] /. DiracTrace -> TR]
Simplify[Contract[amps1 amps2]]

----- Original Message -----

To: <feyncalc@feyncalc.org>
Sent: Thursday, May 15, 2008 1:06 AM
Subject: FermionSpinSum gives unwanted results

> hello,
> i have:
> Ma=SpinorUBar[k1,m].DiracMatrix[mu].SpinorU[p1,m].SpinorUBar[k2,m].DiracMatrix[mu].SpinorU[p2,m]
>
> Mac=ComplexConjugate[Ma] /.mu->nu
>
> amp=Ma Mac //Contract
>
> amps=FermionSpinSum[amp]
>
> but the output of FermionSpinSum does not has Traces, the above code is
> for calculating the unpolorized feynman amplitude of the Moller process.
> can you help me
>

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