Name: Vladyslav Shtabovenko (email_not_shown)
Date: 05/10/16-12:16:49 PM Z


Hi,

I remember fixing a few things in FCApart,

https://github.com/FeynCalc/feyncalc/commit/1225fe13db977a3b834e4867e7d55aa3d523a5bb

https://github.com/FeynCalc/feyncalc/commit/8e859cbe1c3cb24cd1fb6b717781690baa04f3e3

but since that involved introducing two new options, and changing
the old behavior (now scaleless integrals are set to zero, while before
ApartFF kept them) I didn't push that to the stable branch.

With the development version from

Import["https://raw.githubusercontent.com/FeynCalc/feyncalc/master/install.m"]
InstallFeynCalc[InstallFeynCalcDevelopmentVersion -> True]

your example

ex1 = FAD[q1, -k1 - k2 - k3 - k4 + q1] SPD[k1, q1] SPD[k2,
   k1 + k2 + k3 + k4 - q1] SPD[p1, -k1 - k2 - k3 - k4 + q1] SPD[p2,
   q1]
AbsoluteTiming[
  res1 = OneLoop[q1, ex1, OneLoopSimplify -> True];] // First

evaluates, although it takes roughly 82 secs to do so.

It works a bit faster with

AbsoluteTiming[res2 = TID[ex1, q1, UsePaVeBasis -> True];] // First
res2 // PaVeReduce

also here a B11 is left behind, that is actually reducable, not with the
current code settings.

Cheers,
Vladyslav

Am 10.05.2016 um 01:30 schrieb Peter Conkey:
>
> I am using FeynCalc 9.01 in Mathematica 10.4 (The same occurred in FeynCalc 9.0 in Mathematica 10.3).
>
> OneLoop behaves apparently inconsistently as follows :
>
>
>
> example =
> FeynAmpDenominator[PropagatorDenominator[Momentum[q1], 0],
> PropagatorDenominator[Momentum[-k1 - k2 - k3 - k4 + q1], 0]]*
> Pair[Momentum[k1], Momentum[q1]]*
> Pair[Momentum[k2], Momentum[k1 + k2 + k3 + k4 - q1]]*
> Pair[Momentum[p1], Momentum[-k1 - k2 - k3 - k4 + q1]]*
> Pair[Momentum[p2], Momentum[q1]];
>
> OneLoop[q1, %, OneLoopSimplify -> True]
>
> produces an error
>
> FCApart::checkfail:
> Error! Partial fractioning of the loop integral FeynAmpDenominator[PropagatorDenominator[Momentum[q1, D], 0], PropagatorDenominator[-Momentum[k1, D] - Momentum[k2, D] - Momentum[k3, D] - Momentum[k4, D] + Momentum[q1, D], 0]]*(-Pair[Momentum[k1, D], Momentum[q1, D]] - Pair[Momentum[k2, D], Momentum[q1, D]] - Pair[Momentum[k3, D], Momentum[q1, D]] - Pair[Momentum[k4, D], Momentum[q1, D]])^2*Pair[Momentum[q1, D], Momentum[q1, D]] by FCApart has produced an inconsistent result. Evaluation aborted
> 1/2 (-1-Pair[Momentum[k1,D],Momentum[q1,D]]-Pair[Momentum[k2,D],Momentum[q1,D]]-Pair[Momentum[k3,D],Momentum[q1,D]]-Pair[Momentum[k4,D],Momentum[q1,D]])
>
>
>
>
> However
>
> example /.
> { -k1 -k2 -k3-k4 -> -b,
> k1 +k2 +k3 +k4 -> b};
>
>
> OneLoop[q1, %, OneLoopSimplify -> True]
>
> produce a result.
>
>
>
>
>



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