Name: Kornelija Passek-Kumericki Date: 07/10/06-11:52:16 AM Z


Hi!

Defining ScalarProducts before using Tr
causes my version of FC (4.1.03b) run under (Mathematica 4.2)
to produce incorrect results:

Tr[GAD[a].GSD[P].GAD[b].GSD[P]] // InputForm
4*(2*Pair[LorentzIndex[a, D], Momentum[P, D]]*
   Pair[LorentzIndex[b, D], Momentum[P, D]] -
  Pair[LorentzIndex[a, D], LorentzIndex[b, D]]*
   Pair[Momentum[P, D], Momentum[P, D]])

but

ScalarProduct[p, p] = 0

Tr[GAD[a].GSD[p].GAD[b].GSD[p]] // InputForm

gives

2*DiracGamma[LorentzIndex[a, D], D] .
  DiracGamma[Momentum[p, D], D]*Pair[LorentzIndex[b, D],
  Momentum[p, D]]

??!!

Is this a known bug?

Regards,
Kornelija