WHIZARD

Decay Higgs to tau using whizard and pythia 8

Asked by Goran Kacarevic

Dear whizard team,

We want to use Whizard to decay Higgs to tau tau probe the CP properties of the Higgs boson. For this we would like to decay tau's using pythia 8 to save spin correlations. Tau will not decay when $shower_method = "PYTHIA8" is using pythia8.

Do you have any advice how can I use pythia 8 to decay tau's, or maybe example of a sindarin file?
I have tried using $ps_PYTHIA8_config, but still cannot decay taus.

Thank you in advance.

Goran

Question information

Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
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Last reply:
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Juergen Reuter (j.r.reuter) said : 		#1

Dear Goran,
thanks for the report. Indeed, I can confirm that behavior. Did you try to generate a HepMC event file with Whizard parton-level, and then feed it into Pythia8 without using the Whizard-Pythia8 interface? Then it should work to decay the tau leptons.
I quickly checked that when I set up only the Higgsstrahlung process, e+e- -> ZH, and let Pythia8 do all the decays, I also see that Pythia8 decays tau leptons from the Z decay, but not from the Higgs decay. This looks like something special, where it might not hurt to contact also the Pythia authors. But we will also look into the topic ourselves.
Cheers,
    JRR (Juergen)

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Juergen Reuter (j.r.reuter) said : 		#2

Dear Goran,
in the meantime we can confirm that with a standalone Pythia8 this works, so let Whizard write out parton-level LHE events and then read them into Pythia8. Of course, then Pythia8 would use HepMC for the output, which you might have to convert again to LCIO (in case you want to use those). We will for sure look into the issue with the Pythia8 interface, but not on a very short timescale probably.
We hope that for the moment the workaround is sufficient for you.
Best,
    JRR

Revision history for this message
Juergen Reuter (j.r.reuter) said : 		#3

Assuming this has been solved in the mean time. Please open again or raise a new question in case of further problems.