Name: Vladyslav Shtabovenko Date: 03/23/16-07:32:34 PM Z

Hi,

the issue that you encounter in Case II is not really a bug. As
described in the wiki

https://github.com/FeynCalc/feyncalc/wiki/FeynArts#fa_plus_fc

there are functions (like FourVector or FeynAmpDenominator) that appear
both in FeynCalc in FeynArts but have completely different properties,
so that it is not possible to use two packages as the same time without
risking problems.

“Patching” of FeynArts just renames such functions by adding an “FA” in
front, so that now all the offending functions have different names and
no inconsistencies can occur. This way patched FeynArts can work with
FeynCalc without any problems.

However, if you want to use other packages that need FeynArts (like
FeynRules or FormCalc), then of course you need unpatched FeynArts (your
case I, FeynArts loaded via <<FeynArts`). The patched one has many
important functions renamed, so that other packages cannot work properly
anymore.

I would suggest that you use unpatched FeynArts + FeynRules on a
separate Mathematica kernel, then save the results and load them into
the FeynCalc session, where you can process them further.

Cheers,
Vladyslav

Am 23.03.2016 um 17:18 schrieb Xing-Bo Yuan:
> Hi Vladyslav,
>
> Today, I update FeynCalc in my computer. However, one problem is encountered.
>
> I generate the SM model file from FeynRules. It can be used in FeynArts, but not the patched FeynArts with FeynCalc. The details are described below:
>
> My computer information:
> OS: Mac OS X 10.9.5
> MMA: 8.0.0.0
> FeynRules:2.3.19
>
> Case I:
> FeynCalc: 9.0.1
> FeynArts: 3.9
> The FeynCalc is installed by the automatic command in the FeynCalc wiki. During the installation process, FeynArts is automatically installed and patched.
>
> Case II:
> FeynArts: 3.9
> Just downloaded from FeynArts website.
>
>
> I generate the FeynArts model files “SM_Unitary_Gauge.mod” and “SM_Unitary_Gauge.gen” in FeynRules with the default SM model file SM.fr. Then, I load the model file in FeynArts using the command
>
> InitializeModel[“SM_Unitary_Gauge”, GenericModel -> “SM_Unitary_Gauge”]
>
> In case II, It’s OK. In case I, however, I get an error:
>
> TagSetDelayed::tagnf: “Tag FourVector not found in -Overscript[mom_, _]^mu_”.
>
>
> Maybe, the reason is that some codes of FeynArts are not correctly patched in FeynRules 9.0.1. Could you please check if it is a bug? I upload the relevant files in the link
>
> https://www.dropbox.com/s/u4w19pwpdnv4cjq/debug_FeynRules_9.0.1.zip?dl=0
>
> Thank you for your time.
>
>
> Best Regards,
> Xing-Bo Yuan
>