· FeynCalc

Name: Vladyslav Shtabovenko Date: 08/21/17-03:35:07 AM Z

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Previous message: Maksym: “Re: A problem with syntax involving the propagators”
In reply to: Maksym: “How to write quark propagator in 4 dimensions?”

By default QuarkPropagator does not insert an explicit value for the
quantity. You need Explicit for that:

Explicit[QuarkPropagator[{p, m}], Dimension -> 4]

Hence,

f = PolarizationVector[
     k2, \[Mu]] SpinorUBar[p1,
      mp].GA[\[Nu]].(vf - af GA5).QuarkPropagator[{k1 + k2,
       mp}].GA[\[Mu]].SpinorU[k1, mp] SpinorUBar[p3,
      m].GA[\[Nu]].(1 - GA5).SpinorV[p2, 0] //
   Explicit[#, Dimension -> 4] &

Tr[FermionSpinSum[f FCRenameDummyIndices[ComplexConjugate[f]]]]

Am 19.08.2017 um 21:38 schrieb Maksym:
> I write the amplitude as
> f = PolarizationVector[
> k2, \[Mu]] SpinorUBar[p1,
> mp].GA[\[Nu]].(vf - af GA5).QuarkPropagator[{k1+k2},mp].GA[\[Mu]].SpinorU[
*> k1, mp] SpinorUBar[p3, m].GA[\[Nu]].(1

GA5).SpinorV[p2, 0]*
>
> But when evaluating the trace f ComplexConjugate[f] the output writes Error! DiracTrick has encountered a fatal problem and must abort the \
> computation. The problem reads: Incorrect combination of dimensions \
> and g^5 scheme! >>
>
> Could you please tell me how to define the quark propagator in 4 dimensions?
>

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In reply to: Maksym: “How to write quark propagator in 4 dimensions?”