Name: V. Shtabovenko Date: 09/21/19-11:32:42 AM Z

Dear FeynCalc users,

since FeynCalc 9.3 is about to be released quite soon, here is
a short summary of the most recent changes:

* FeynArts, PHI ans TRACER

The new syntax to load FeynArts is

$LoadAddons={“FeynArtsLoader”};
<<FeynCalc`

This is because technically FeynArts is now loaded via an add-on
called FeynArtsLoader. This makes it more consistent and easier
to maintain.

PHI, Frederik’s addon for ChPT calculation was moved to a separate
repository:

https://github.com/FeynCalc/PHI

As some of you probably know, PHI is
currently not fully compatible with FeynCalc in the sense that
many things do not work as they should. We certainly plan to
improve on that, but this is not a short term goal. Anyhow, PHI
is now also an add-on, so if you install it from the repository
and want to run it, use

$LoadAddons={“PHI”};
<<FeynCalc`

Regarding TARCER, it is now also a proper add-on and should be loaded
via

$LoadAddons={“TARCER”};
<<FeynCalc`

The old syntax with $LoadFeynArts, $LoadPhi and $LoadTARCER is deprecated
but still works.

* Gamma 5

We refactored the mechanism to switch between different g^5 schemes,
introducing new routines

FCSetDiracGammaScheme[“scheme”] and FCGetDiracGammaScheme[]

Available schemes are “NDR”, “BMHV”, “Larin” and “NDR-Drop”

The two routines are fully documented and more infos are available in the
documentation center. In a nut shell, instead of writing say

$BreitMaison=True;
….

you should now use

FCSetDiracGammaScheme[“BMHV”]
…

The old syntax with $BreitMaison and $Larin still works, though.

Furthermore, we modified the behavior of the NDR scheme, so that now it will
not spam you with warning messages on any occurrence of traces with one g^5,
but rather keep such traces unevaluated. So if you know how to deal with
them, you can process the output accordingly.

A new scheme we added is “NDR-Drop” which behaves exactly like NDR, with
the exception that any remaining traces with one g^5 that cannot be
simplified any
further, will be set to zero. This is meant for calculations where such
traces may occur but you know in advance that they do not contribute to
the final result. For more infos, see the documentation on DiracTrace
and FCSetDiracGammaScheme.

Cheers
Vladyslav