MadGraph5_aMC@NLO

Treatment of unstable particles

Asked by Kristian Moffat

Where can I find documentation on the way in which MG5_aMC@NLO treats unstable particles?

I want to perform a calculation in which two propagating unstable particles have nearly equal masses and overlapping widths. The literature on this subject implies that I need to use a modified form of the propagator (more general than the usual Breit-Wigner form). I'd like to know if Breit-Wigner is the default assumption of MadGraph and if it is possible to modify this?

Thanks

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Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

Yes Breit-Wigner is the default.
Information on how to change that default is include in that paper:
arXiv:1308.1668
(see Section UFO and ALOHA)

Cheers,

Olivier

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Kristian Moffat (kpmoffat) said : 		#2

Thanks Olivier Mattelaer, that solved my question.