Define the Fermi theory with CalcHEP

Asked by Yong Du on 2021-03-06

Hi,

After some trials, it looks to me that I can not define the Fermi theory directly within CalcHEP. So, is it true that CalcHEP only allows the definition of renormalizable Lagrangians? If not, could you show me how to define the Fermi theory? Thanks.

Best,
Yong

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Alexander Belyaev
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Best Alexander Belyaev (alexander.belyaev) said :
#1

No it is not true, you can work with any theory in CalcHEP, including an effective one, e.g.
4 fermion interactions.

You should simply use aux fields to construct cintact interactions -- see manual. Or you can use LnHEP -- if you enter there lagrangian with 4 fermion interactions, it will automatically generate correct model for you with aux fields.
See examples of the models at HEPMDB (hepmdb.soton.ac.uk) -- HEP Model Data Base,
e.g. EFT models with 4 fermion DM interactions.

Using aux fields you cn create effective operators of any dimensions, not only dimension 6 ones.

Regards,
Alexander

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Yong Du (fallive) said :
#2

Thank you a lot! I got the idea now.

Best,
Yong

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Yong Du (fallive) said :
#3

Thanks Alexander Belyaev, that solved my question.