scaling of of EM and weak coupling constants

Asked by chris

Hello,

I've been studying asymptotic cross sections recently, and was checking on how the running of the coupling constants are calculated in clachep. I can see that the QCD coupling scales with energy; however, I couldn't find anything about the scaling of the EM or weak couplings in the manual. I was wondering if calchep calculates the scaling of these couplings as well, or just the strong coupling's?

Thanks,

Chris

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Alexander Pukhov (pukhov) said :
#1

The run  of EW couplings is not implemented in CalcHEP.

You can redefine them ( say, via parameter Q). But you have to take into
account that in such case  masses of Z and W will be running as well.

Best

    Alexander Pukhov

On 05/07/2018 12:22 PM, chris wrote:
> Question #668701 on CalcHEP changed:
> https://answers.launchpad.net/calchep/+question/668701
>
> Description changed to:
> Hello,
>
> I've been studying asymptotic cross sections recently, and was checking
> on how the running of the coupling constants are calculated in clachep.
> I can see that the QCD coupling scales with energy; however, I couldn't
> find anything about the scaling of the EM or weak couplings in the
> manual. I was wondering if calchep calculates the scaling of these
> couplings as well, or just the strong coupling's?
>
> Thanks,
>
> Chris
>

Revision history for this message
chris (cmwedin) said :
#2

Are there any plans to implement the running of the EW couplings in a future version of calchep? If not, do you have a general idea of the files that would need to be modified to implement the running on ones own?

Thanks,

Chris

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Alexander Belyaev (alexander.belyaev) said :
#4

To implement running EW coupling
one should do conceptually the same as it was done for strong coupling --
to implement it in the program and link it to CalcHEP via extlib.mdl
The name of the respective function should be used in the func.mdl part of the model.
It is quite easy to do this.

Can you help with this problem?

Provide an answer of your own, or ask chris for more information if necessary.

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