Changing the gauge in the c interface of CalcHEP.

Asked by Jacob

What is the command I need to change the gauge in the c code interface of CalcHEP? Specifically, I would like to change from Feynman gauge to unitary gauge.


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Neil Christensen
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Neil Christensen (neil-christensen-qft) said :

Hi Jacob,

You have to change the gauge before producing the numerical c code. The numerical code is either for Feynman gauge or for unitary gauge but cannot be switched between the two after being produced. Please see Section 4.1 of the manual.


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Alexander Belyaev (alexander.belyaev) said :

Dear Both,
I guess Jacob means c-code for
"Using CalcHEP as a matrix elements generator for other packages" -- section
10 of our write up.

For production process, there is a parameter UG, which controls the gauge,
while for decay, I am not sure.

May be Sasha Pukhov, knows the answer?

Sasha (Pukhov),
could you choose the gauge for decay when using CalcHEP in the c-code?

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Best Neil Christensen (neil-christensen-qft) said :

Good point. The gauge is determined by the routine "getMEcode". You can find documentation in Section 10.7 of the recent CH paper, or 10.5 of the manual linked on the CH website.

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Jacob (jb18g10) said :

Thanks Neil Christensen, that solved my question.