Name: V. Shtabovenko Date: 11/06/19-10:10:04 PM Z
Hi,
apart from loading the unitarity gauge extension you also need to set
the
corresponding gauge rules in CreateFeynAmp
| CreateFeynAmp[diags,GaugeRules->{FAGaugeXi[Z]->Infinity,FAGaugeXi[W]->Infinity,FAGaugeXi[A | S]->1}] |
BTW, the amplitudes are generated not by FeynCalc but by FeynArts,
which
is a different software.
The included examples that use unitarity gauge merely exploit the fact
the when expanding in the inverse of the W-mass, the gauge terms are
neglected, so that g^{mu nu}/m_W^2 is the only piece that survives.
Perhaps I should have done it in a more explicit way.
Cheers,
Vladyslav
Am 06.11.19 um 20:06 schrieb Noah Steinberg:
> Hello, I’m trying to use Feyncalc 9.3 to do some tree level
calculations in unitary gauge but I cannot seem to get it to work
correctly.
>
> Let’s say I am just looking at the Z exchange diagrams for WW->WW
scattering. Each of these should have a Z propagator that looks like ~
(g_{\mu,\nu} - k_{\mu}k_{\nu}/mz^{2}) in unitary gauge. However
even with unitary gauge loaded, the amplitudes returned by feyncalc only
include the g_{\mu,\nu} pieces.
>
> I have tried using examples that are included and all of these
amplitudes have the same problem.
>
> Thank you.
>