Name: Shrihari (email_not_shown)
Date: 02/11/14-02:59:42 PM Z


I am having some problems getting OneLoop[...] to work. I give below a simplified example, where I think (part of) my problem lies.

I notice that OneLoop[...] does not cancel the two terms in:
 ( 4 (l^mu l^nu) - l^2 g^(mu nu) )/f(l^2) where f is symmetric in l.
The result should be zero.

I have a small test code to show this, given below.
I expect the results Res1 and Res2 to be the same.
Res2 is ok while Res1 seems to have another term.

Am I doing something wrong?

I don't seem to be able to attach a file to this email (through the web-interface), so have placed the Mathematica notebook at:

Thanks for any help.


(* The notebook file at the above link also contains the results.
 Res1 and Res2 should be the same, but don't seem to be. *)

tst = FeynAmpDenominator[
   PropagatorDenominator[Momentum[l, D], Sqrt[mf^2]],
   PropagatorDenominator[Momentum[l, D], Sqrt[mf^2]],
   PropagatorDenominator[Momentum[l, D],
     Pair[LorentzIndex[\[Mu], D], LorentzIndex[\[Nu], D]] +
    4*mf*Pair[LorentzIndex[\[Mu], D], Momentum[l, D]]*
     Pair[LorentzIndex[\[Nu], D], Momentum[l, D]] -
    mf*Pair[LorentzIndex[\[Mu], D], LorentzIndex[\[Nu], D]]*
     Pair[Momentum[l, D], Momentum[l, D]])

Res1=PaVeReduce[OneLoop[l, tst]]

tst2 = FeynAmpDenominator[
   PropagatorDenominator[Momentum[l, D], Sqrt[mf^2]],
   PropagatorDenominator[Momentum[l, D], Sqrt[mf^2]],
   PropagatorDenominator[Momentum[l, D], Sqrt[mf^2]]]*(mf^3*
    Pair[LorentzIndex[\[Mu], D], LorentzIndex[\[Nu], D]])

Res2 = OneLoop[l, tst2]

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