changing model parameters

Asked by Nikhil Bachhawat on 2020-05-12

Hi,

I was trying to change the triple Higgs self-coupling value in SM. I know that there are .mdl files in the share/models folder. In that the SM.mdl file seems to have some variables that would be used to calculate the triple higgs coupling. Also there is a F90 file with the gh3 variable in it in the src/models folder.

I wanted to know if changing variable values in these files is the way to change the coupling or is there a better way? I do not want to affect any other properties of the SM model and so directly changing gh3 would be ideal I think. But whizard does not allow access to that variable from the interactive session.

Thanks,
Nikhil

Question information

Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
Solved by:
Juergen Reuter
Solved:
2020-05-12
Last query:
2020-05-12
Last reply:
2020-05-12
Best Juergen Reuter (j.r.reuter) said : #1

Hi Nikhil,
of course you can edit the file src/models/parameters.SM.f90 and then recompile. However, this is not
really the intended way. The intended way is that you use the model SM_ac instead of SM and then you
can directly set the parameter fac_gh3 which serves as a kappa parameter for the triple Higgs coupling.
You also have to set ka = 0 and kz = 0 I think. Otherwise there are anomalous triple gauge couplings, please
check. The third possibility is that you take a UFO model with a modified triple Higgs coupling.
Cheers,
   JRR

Nikhil Bachhawat (nikhilb1997) said : #2

Thanks Juergen Reuter, that solved my question.