Missing intermediate resonances in event

Asked by Philipp Pigard on 2012-03-13

Using an implementation of the MCPM (where the relevant Higgs bosons are h1 and h2), I generated some events using ME5:

p p > h1 | h2 > m+ m-

The generated events appear to be "correct" in their physics properties, but for some of the generated events, there are no intermediary Higgs bosons in the LHE files. The respective events therefore appear like

c c~ > m+ m-

where the particle count in the events header confirms that only 4 particles were involved in the event.

Since there are no 4-verticees in the model, I am confused about those events showing up.

Thanks for any help.

Philipp P.

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Solved by:
Johan Alwall
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Best Johan Alwall (johan-alwall) said : #1

Hello Philippe.

Intermediate resonances are only included in the event file only if they are considered onshell, i.e. their invariant mass is between M-bwcutoff*Gamma and M+bwcutoff*Gamma. The value for bwcutoff is set in the run_card, it is by default 15.

All the best,

Philipp Pigard (p-pigard) said : #2

Thanks Johan Alwall, that solved my question.