Name: Vladyslav Shtabovenko (email_not_shown)
Date: 04/05/14-09:40:34 PM Z

Dear all,

I would like to report two bugs I encountered in Feyncalc 8.2 (latest
version). I'm using Mathematica 9, but the bugs are not really related
to that.

First of all, in Models/FCQCDLorentz.gen there should be a
"$FermionLines = True" statement, since otherwise FeynArts generates
diagrams without Dirac traces and FeynCalc subsequently fails to compute
the color trace. This is fixed in Phi, but not in FeynCalc itself.

Then, in general/Collect3.m, there is a regression bug related to the
MonomialList function. In FC8.1 there was a condition to use the
FeynCalc's version of MonomialList for Mathematica below version 6. For
some reason this condition was removed in FC8.2. The problem is, that
Mathematica's built-in MonomialList doesn't have the Option
"CoefficientDomain -> RationalFunctions", which makes all functions that
rely on Collect3 fail.

You can easily reproduce the bugs by trying to run
Because of the missing Dirac traces and the broken MonomialList, the
computation fails on FC8.2.

Please find the patch that fixes this problems attached.

Just in case, I also attach a patch for the FeynArts 3.7, since
automatic patching doesn't seem to work with Mathematica 9. The patch is
just what happens to FA 3.7 after you run

<< "HighEnergyPhysics`Phi`Extras`FAPatch`"
$FeynArtsDirectory =

If you need to use FeynCalc 8.2 now and you absolutely cannot wait until
developers release the new version, here's a quick fix guide on Linux:

1) Install fresh Feyncalc via
2) Copy the attached patches to

3) In the console run
    cd ~/.Mathematica/Applications/HighEnergyPhysics
    patch -p0 < feynarts.patch
    patch -p0 < fc82.patch
4) Restart Mathematica, run fcexamples/qcdghostse2loopnew2.nb. and check
    that you get the same results as in the notebook

P.S. Correct me if I'm wrong but it looks like in the CVS we still have
FC8.1, not FC8.2. Also, with the instructions on it is impossible to check
out the repository :(


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