MadGraph5_aMC@NLO

setting muR_over_ref in script

Asked by Kristin Lohwasser

Dear all!

I am trying to run aMCatNLO with changed scale defintion using a script.

Therefore I am trying to set the scales in the script by doing:
set muF2_over_ref 2
...

This however does not seem to work (as you can see below)

INFO: modify parameter lhaid of the run_card.dat to 11000
set muR_over_ref 0.5
WARNING: invalid set command muR_over_ref 0.5
set muF1_over_ref 2
WARNING: invalid set command muF1_over_ref 2
set muF2_over_ref 2
WARNING: invalid set command muF2_over_ref 2
set ebeam2 3500
INFO: modify parameter ebeam2 of the run_card.dat to 3500

Is there any trick to this?

Thanks a lot and best
Kristin

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Stefano Frixione (stefano-frixione) said : 		#1

Hi Kristin,
there may be a problem of lowercase/uppercase somewhere in the python code, that prevents those
entries from being read correctly. We'll take a look at this.

In the meanwhile, I'm just wondering why you want to recompute a cross section by changing those
scales. The information on scale (and PDF) dependencies is automatically kept in all computations,
without rerunning anything, provided that in inputs you set
 .true. = reweight_scale ! reweight to get scale dependence
and
 .true. = reweight_PDF ! reweight to get PDF uncertainty
for scales and PDFs respectively.
These operations will save weights in the event file, that you can use to compute scale and PDF
uncertainties just by filling histograms in the same way as you do normally.
Please take a look at answer #4 in the following thread:
  https://answers.launchpad.net/madgraph5/+question/227054
which should give you an explicit example relevant to scale uncertainties.
Regards, Stefano.

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