MadGraph5_aMC@NLO

Producing W->3pi process

Asked by Yurii Maravin

Dear all,

I am trying to produce a W->3 pi decay in NLO accuracy, and I have an issue. If I produce an undecayed W in aMC@NLO and decay it in pythia, the W width is always zero, and I need to have off-shell contributions due to the specifics of the analysis. I think aMC@NLO ignores the width of W if it is not decayed. However, if I try to decay W in aMC@NLO to 3 pions I get "No particle pi+ in the model" error.

Is there a way to produce undecayed Ws in aMC@NLO with non-zero width? Or any workaround I could use?
Thanks much in advance!

Yurii

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Are you looking at tau decay into three pions?
If yes, the best might be to generate NLO sample up to the tau lepton,
then use either pythia or the taola or the tau_decay model in conjuction to madspin to decay those tau into three pions.

If not, then i have no clue how to do it.

Cheers,

Olivier

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Yurii Maravin (maravin) said : 		#2

Hi Olivier,

no, it is a rare W->3pi decay... Thank you for looking into this!

Cheers,
Yurii

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Rihla Booking (rihla) said (last edit ): 		#3
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