scale for reweighting pdfs

Asked by Hannes Jung on 2018-10-26

Dear aMCatNLO experts

I would like to read from the lhe file the scale at which the pdf was evaluated.
I assume, it is not the variable SCALEUP, since for Z inclusive at NLO I get an event which looks like:

  <event>
  5 0 0.12804977E+04 0.14635717E+02 0.75467711E-02 0.14596210E+00
        2 -1 0 0 501 0 0.00000000E+00 0.00000000E+00 0.23548594E+03 0.23548616E+03 0.32000000E+00 0.0000E+00 0.9000E+01
       -2 -1 0 0 0 501 0.00000000E+00 0.00000000E+00 -.89686201E+01 0.89743270E+01 0.32000000E+00 0.0000E+00 0.9000E+01
       23 2 1 2 0 0 0.00000000E+00 0.00000000E+00 0.22651732E+03 0.24446049E+03 0.91928409E+02 0.0000E+00 0.0000E+00
      -11 1 3 3 0 0 0.23024872E+02 0.43837505E+01 0.81141776E+01 0.24803264E+02 0.51099893E-03 0.0000E+00 0.9000E+01
       11 1 3 3 0 0 -.23024872E+02 -.43837505E+01 0.21840315E+03 0.21965722E+03 0.51099893E-03 0.0000E+00 0.9000E+01
#aMCatNLO 1 0 0 1 2 0.44558735E+01 0.00000000E+00 9 5 0 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00
  <rwgt>
   <wgt id='1001'> 0.12805E+04 </wgt>
   <wgt id='1002'> 0.12324E+04 </wgt>
   <wgt id='1003'> 0.13391E+04 </wgt>
   <wgt id='1004'> 0.16835E+04 </wgt>
   <wgt id='1005'> 0.16012E+04 </wgt>
   <wgt id='1006'> 0.17868E+04 </wgt>
   <wgt id='1007'> 0.95461E+03 </wgt>
   <wgt id='1008'> 0.93007E+03 </wgt>
   <wgt id='1009'> 0.98286E+03 </wgt>
  </rwgt>
  </event>

where SCALEUP=0.14635717E+02, while I would naively assume the scale is the Z-boson mass.
Can I extract the scale from the line #aMCatNLO ?

Thanks a lot

Best

Hannes

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
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Last query:
2018-10-26
Last reply:
2018-10-26

Hi,

If you want to have that information written in the event file,
you need to activate the information for the re-weighitng:
store_rwgt_info

In that case, you will have a LOT more information since the scale that you ask for is not unique at NLO. So you will have have the list of events and couter-events used for gernerating that events and all the information at which value of x --and the scale-- the pdf is used.

If you need to understand the format of that (very complex) information,
I would advise to read the file lhe_parser.py where this is parsing is already done with plenty of comment.

Note that if you want to perform any PDF rescaling/... you can use the code systematics.py
whcih use the information from store_rwgt_info to allow the computation of a lot of systematics.

Cheers,

Olivier

On 26 Oct 2018, at 10:57, Hannes Jung <<email address hidden><mailto:<email address hidden>>> wrote:

New question #675573 on MadGraph5_aMC@NLO:
https://answers.launchpad.net/mg5amcnlo/+question/675573

Dear aMCatNLO experts

I would like to read from the lhe file the scale at which the pdf was evaluated.
I assume, it is not the variable SCALEUP, since for Z inclusive at NLO I get an event which looks like:

 <event>
 5 0 0.12804977E+04 0.14635717E+02 0.75467711E-02 0.14596210E+00
       2 -1 0 0 501 0 0.00000000E+00 0.00000000E+00 0.23548594E+03 0.23548616E+03 0.32000000E+00 0.0000E+00 0.9000E+01
      -2 -1 0 0 0 501 0.00000000E+00 0.00000000E+00 -.89686201E+01 0.89743270E+01 0.32000000E+00 0.0000E+00 0.9000E+01
      23 2 1 2 0 0 0.00000000E+00 0.00000000E+00 0.22651732E+03 0.24446049E+03 0.91928409E+02 0.0000E+00 0.0000E+00
     -11 1 3 3 0 0 0.23024872E+02 0.43837505E+01 0.81141776E+01 0.24803264E+02 0.51099893E-03 0.0000E+00 0.9000E+01
      11 1 3 3 0 0 -.23024872E+02 -.43837505E+01 0.21840315E+03 0.21965722E+03 0.51099893E-03 0.0000E+00 0.9000E+01
#aMCatNLO 1 0 0 1 2 0.44558735E+01 0.00000000E+00 9 5 0 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00
 <rwgt>
  <wgt id='1001'> 0.12805E+04 </wgt>
  <wgt id='1002'> 0.12324E+04 </wgt>
  <wgt id='1003'> 0.13391E+04 </wgt>
  <wgt id='1004'> 0.16835E+04 </wgt>
  <wgt id='1005'> 0.16012E+04 </wgt>
  <wgt id='1006'> 0.17868E+04 </wgt>
  <wgt id='1007'> 0.95461E+03 </wgt>
  <wgt id='1008'> 0.93007E+03 </wgt>
  <wgt id='1009'> 0.98286E+03 </wgt>
 </rwgt>
 </event>

where SCALEUP=0.14635717E+02, while I would naively assume the scale is the Z-boson mass.
Can I extract the scale from the line #aMCatNLO ?

Thanks a lot

Best

Hannes

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You received this question notification because you are an answer
contact for MadGraph5_aMC@NLO.

Hannes Jung (hannes.jung) said : #2

perfect, thanks a lot for the fast answer
Best
Hannes

On 26. Oct 2018, at 11:12, Olivier Mattelaer <<email address hidden><mailto:<email address hidden>>> wrote:

Your question #675573 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/675573

   Status: Open => Answered

Olivier Mattelaer proposed the following answer:
Hi,

If you want to have that information written in the event file,
you need to activate the information for the re-weighitng:
store_rwgt_info

In that case, you will have a LOT more information since the scale that
you ask for is not unique at NLO. So you will have have the list of
events and couter-events used for gernerating that events and all the
information at which value of x --and the scale-- the pdf is used.

If you need to understand the format of that (very complex) information,
I would advise to read the file lhe_parser.py where this is parsing is already done with plenty of comment.

Note that if you want to perform any PDF rescaling/... you can use the code systematics.py
whcih use the information from store_rwgt_info to allow the computation of a lot of systematics.

Cheers,

Olivier

On 26 Oct 2018, at 10:57, Hannes Jung
<<email address hidden><mailto:<email address hidden>>>
wrote:

New question #675573 on MadGraph5_aMC@NLO:
https://answers.launchpad.net/mg5amcnlo/+question/675573

Dear aMCatNLO experts

I would like to read from the lhe file the scale at which the pdf was evaluated.
I assume, it is not the variable SCALEUP, since for Z inclusive at NLO I get an event which looks like:

<event>
5 0 0.12804977E+04 0.14635717E+02 0.75467711E-02 0.14596210E+00
      2 -1 0 0 501 0 0.00000000E+00 0.00000000E+00 0.23548594E+03 0.23548616E+03 0.32000000E+00 0.0000E+00 0.9000E+01
     -2 -1 0 0 0 501 0.00000000E+00 0.00000000E+00 -.89686201E+01 0.89743270E+01 0.32000000E+00 0.0000E+00 0.9000E+01
     23 2 1 2 0 0 0.00000000E+00 0.00000000E+00 0.22651732E+03 0.24446049E+03 0.91928409E+02 0.0000E+00 0.0000E+00
    -11 1 3 3 0 0 0.23024872E+02 0.43837505E+01 0.81141776E+01 0.24803264E+02 0.51099893E-03 0.0000E+00 0.9000E+01
     11 1 3 3 0 0 -.23024872E+02 -.43837505E+01 0.21840315E+03 0.21965722E+03 0.51099893E-03 0.0000E+00 0.9000E+01
#aMCatNLO 1 0 0 1 2 0.44558735E+01 0.00000000E+00 9 5 0 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00
<rwgt>
 <wgt id='1001'> 0.12805E+04 </wgt>
 <wgt id='1002'> 0.12324E+04 </wgt>
 <wgt id='1003'> 0.13391E+04 </wgt>
 <wgt id='1004'> 0.16835E+04 </wgt>
 <wgt id='1005'> 0.16012E+04 </wgt>
 <wgt id='1006'> 0.17868E+04 </wgt>
 <wgt id='1007'> 0.95461E+03 </wgt>
 <wgt id='1008'> 0.93007E+03 </wgt>
 <wgt id='1009'> 0.98286E+03 </wgt>
</rwgt>
</event>

where SCALEUP=0.14635717E+02, while I would naively assume the scale is the Z-boson mass.
Can I extract the scale from the line #aMCatNLO ?

Thanks a lot

Best

Hannes

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