MadGraph5_aMC@NLO

Pythia 8 Tunings MG5@LO and MG5aMC

Asked by Richard Ruiz

Hi Folks,

Just a quick question or two. What are the default PY8 tunes for MG5@LO+PY8 or MG5aMC? Is it possible to switch tunes without having to run PY8 externally and independently? If so, where can I find documentation on this? Thanks!

best,
richard

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MadGraph5_aMC@NLO Edit question
Assignee:
Stefan Prestel Edit question
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Stefan Prestel (prestel) said : 		#1

Hi Richard,

The default Pythia 8 tune for MG5@LO+PY8 or MG5aMC is identical to the default in your Pythia installation. You can find what the default tune is (and the documentation of how you switch between tunes) at

http://home.thep.lu.se/~torbjorn/pythia82html/Welcome.html

under the section "Tunes".

If you want to use any Pythia 8 settings from within MG5 without running Pythia 8 externally, then, as soon as the message "Do you want to edit a card (press enter to bypass editing)?" comes up, you choose to edit the pythia8 card. In this card, you can use all the Pythia 8 settings you want. The Pythia online documentation (see above) should be a good resource to browse. If you e.g. want to change from the current default tune to the older Tune 4C, you can add the line

Tune:pp = 5

in your Pythia card.

Hope that helps,
Stefan

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