problem in showering

Asked by Soumyadip Barman on 2020-07-02

Hello,

I am producing p p > t t~ [QCD]
I am trying to use NLO and shower with Pythia. But getting some error message when the showering starts. I don't know what's going wrong from my side. Please suggest something on this matter.

This is the output I am getting -

   --------------------------------------------------------------
      Summary:
      Process p p > t t~ [QCD]
      Run at p-p collider (6500.0 + 6500.0 GeV)
      Number of events generated: 10000
      Total cross section: 6.762e+02 +- 4.0e+00 pb
   --------------------------------------------------------------
      Scale variation (computed from LHE events):
          Dynamical_scale_choice -1 (envelope of 9 values):
              6.610e+02 pb +9.1% -11.4%
   --------------------------------------------------------------

INFO: The /afs/cern.ch/work/s/sobarman/private/Package/Madgraph/MG5_aMC_v2_6_7/NLO_ttbar/Events/run_04/events.lhe.gz file has been generated.

INFO: Events generated
reweight -from_cards
decay_events -from_cards
INFO: Preparing MCatNLO run
WARNING: Trying to shower events using the same PDF in the shower as used in the generation of the events using LHAPDF. However, no valid LHAPDF installation found with the needed PDF set. Will use default internal PDF for the shower instead. To use the same set as was used in the event generation install LHAPDF and set the path using "set /path_to_lhapdf/bin/lhapdf-config" from the MadGraph5_aMC@NLO python shell
INFO: Compiling MCatNLO for PYTHIA6Q...

***** Now ready for showering 10000 events with PYTHIA6Q

rivate/Package/Madgraph/MG5_aMC_v2_6_7/NLO_ttbar/MCatNLO/objects/analysis_HwU_pp_ttx.o', needed by `PY_EXE_DEFAULT'. Stop.
mv: cannot stat ‘PY_EXE_DEFAULT’: No such file or directory
chmod: cannot access ‘/afs/cern.ch/work/s/sobarman/private/Package/Madgraph/MG5_aMC_v2_6_7/NLO_ttbar/MCatNLO/PY_EXE_DEFAULT’: No such file or directory
mv: cannot stat ‘PY_EXE_DEFAULT’: No such file or directory

Error detected in "launch auto "
write debug file /afs/cern.ch/work/s/sobarman/private/Package/Madgraph/MG5_aMC_v2_6_7/NLO_ttbar/run_04_tag_1_debug.log
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
aMCatNLOError : Compilation failed, check /afs/cern.ch/work/s/sobarman/private/Package/Madgraph/MG5_aMC_v2_6_7/NLO_ttbar/mcatnlo.log for details
quit
INFO:
MG5_aMC>exit

********************************************
I have placed the log file in my public: /afs/cern.ch/work/s/sobarman/public/Madgraph

********************************************
I guess there is a problem in selecting the "ANALYSE" in the shower_card. Can you please also elaborate on how can I select that file?

********************************************
Also one of my objectives is to observe the negative weighted events. Please let me know how I can see that part as well.

Thanks,
Soumyadip

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Paolo Torrielli Edit question
Solved by:
Paolo Torrielli
Solved:
2020-07-04
Last query:
2020-07-04
Last reply:
2020-07-04

Hello,

it may be due to the PDF. Try setting pdfcode = 0 in the shower_card.dat.

The problem with Pythia6 is that its development has been discontinued,
so I'm not even sure it complies with LHAPDF6.

In all physics applications I would strongly suggest to use Pythia8 rather
than Pythia6.

Cheers.
Paolo

Hello,

Your suggestions work. Also, I have tried using Pythia8. It works fine for it.

My other question was to check negative weighted events.

1. I want to check the negative weighted events in the summary info. But it is not showing any information regarding that. Probably it was available in the older version in the name of "fraction of negative weighted events". So, can you suggest how can I get the information about the negative weighted events?

2. Is there any way that I can print the information of negative weighted events i.e check event by event?

Thanks,
Soumyadip

You can just read the lhe file and count the number of positive/negative weights.

Cheers,

Olivie

  <initrwgt>
    <weightgroup name='scale_variation -1' combine='envelope'>
      <weight id='1001'> dyn= -1 muR=0.10000E+01 muF=0.10000E+01 </weight>
      <weight id='1002'> dyn= -1 muR=0.20000E+01 muF=0.10000E+01 </weight>
      <weight id='1003'> dyn= -1 muR=0.50000E+00 muF=0.10000E+01 </weight>
      <weight id='1004'> dyn= -1 muR=0.10000E+01 muF=0.20000E+01 </weight>
      <weight id='1005'> dyn= -1 muR=0.20000E+01 muF=0.20000E+01 </weight>
      <weight id='1006'> dyn= -1 muR=0.50000E+00 muF=0.20000E+01 </weight>
      <weight id='1007'> dyn= -1 muR=0.10000E+01 muF=0.50000E+00 </weight>
      <weight id='1008'> dyn= -1 muR=0.20000E+01 muF=0.50000E+00 </weight>
      <weight id='1009'> dyn= -1 muR=0.50000E+00 muF=0.50000E+00 </weight>
    </weightgroup>
  </initrwgt>
  </header>
  <init>
   2212 2212 0.65000000E+04 0.65000000E+04 -1 -1 244800 244800 -4 1
 0.68083127E+03 0.26308972E+01 0.13094024E+04 0
  </init>
  <event>
  4 0 0.13094024E+04 0.99286714E+02 0.75467711E-02 0.10637299E+00
       21 -1 0 0 501 502 0.00000000E+00 0.00000000E+00 0.98147846E+02 0.98147846E+02 0.00000000E+00 0.0000E+00 0.9000E+01
       21 -1 0 0 502 503 0.00000000E+00 0.00000000E+00 -.56701329E+03 0.56701329E+03 0.00000000E+00 0.0000E+00 0.9000E+01
        6 1 1 2 501 0 -.67609886E+02 -.25682615E+02 -.32621134E+02 0.19032559E+03 0.17300000E+03 0.0000E+00 0.9000E+01
       -6 1 1 2 0 503 0.67609886E+02 0.25682615E+02 -.43624431E+03 0.47483554E+03 0.17300000E+03 0.0000E+00 0.9000E+01
#aMCatNLO 1 0 0 2 4 0.24556574E+02 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'> 0.13094E+04 </wgt>
   <wgt id='1002'> 0.10308E+04 </wgt>
   <wgt id='1003'> 0.17079E+04 </wgt>
   <wgt id='1004'> 0.13458E+04 </wgt>
   <wgt id='1005'> 0.10561E+04 </wgt>
   <wgt id='1006'> 0.17613E+04 </wgt>
   <wgt id='1007'> 0.12422E+04 </wgt>
   <wgt id='1008'> 0.98168E+03 </wgt>
   <wgt id='1009'> 0.16134E+04 </wgt>
  </rwgt>
  </event>
  <event>

********************************************************************************
I am confused a little. I can figure out the kinematic parts. But I am unable to figure out the weight information.

   <wgt id='1001'> 0.13094E+04 </wgt>
   <wgt id='1002'> 0.10308E+04 </wgt>
   <wgt id='1003'> 0.17079E+04 </wgt>
   <wgt id='1004'> 0.13458E+04 </wgt>
   <wgt id='1005'> 0.10561E+04 </wgt>
   <wgt id='1006'> 0.17613E+04 </wgt>
   <wgt id='1007'> 0.12422E+04 </wgt>
   <wgt id='1008'> 0.98168E+03 </wgt>
   <wgt id='1009'> 0.16134E+04 </wgt

The above part is weight information i.e it is positive for positive weighted events and negative for negative weighted events. Is my understanding correct?
And can you please point out any document for understanding the LHE format?

Thanks,
Soumyadip

Hi,

the negative weight fraction can be directly deduced from the summary info.
In your Events/run_0* folder, you should just open file res_2.txt and read
the last two lines, which should look similar to

Total ABS and
Total:
                      1.12510172e+03 +- 5.0185e+00 (4.4605e-01%)
                      6.80633632e+02 +- 3.8276e+00 (5.6235e-01%)

The fraction of negative weights is just

[(Total ABS) - Total] / [2 (Total ABS)].

If you want to read the fraction of negative weights directly from the LHE file,
you just need to recall that, according to the Les Houches Accord, the event weight
is the third entry in the event header, i.e. in your event

 <event>
 4 0 0.13094024E+04 0.99286714E+02 0.75467711E-02 0.10637299E+00

the weight is 0.13094024E+04 (positive in this case).

You can use the programs in the Utilities folder of the generated process
to automatically read the number of negative weights from LHE file.

Just go in Utilities, type ‘make check_events’, then go in Event/run_*,
gunzip the event file, execute '../../Utilities/check_events’ and respond
to the prompt questions (your entries should be ‘events.lhe’, 1, 1, 1, -1, -1)
and at the end of the execution the program should tell you the fraction
of negative weights in the LHE file.

Cheers,
Paolo

> On 4 Jul 2020, at 16:10, Soumyadip Barman <email address hidden> wrote:
>
> Question #691640 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/691640
>
> Status: Answered => Open
>
> Soumyadip Barman is still having a problem:
> <initrwgt>
> <weightgroup name='scale_variation -1' combine='envelope'>
> <weight id='1001'> dyn= -1 muR=0.10000E+01 muF=0.10000E+01 </weight>
> <weight id='1002'> dyn= -1 muR=0.20000E+01 muF=0.10000E+01 </weight>
> <weight id='1003'> dyn= -1 muR=0.50000E+00 muF=0.10000E+01 </weight>
> <weight id='1004'> dyn= -1 muR=0.10000E+01 muF=0.20000E+01 </weight>
> <weight id='1005'> dyn= -1 muR=0.20000E+01 muF=0.20000E+01 </weight>
> <weight id='1006'> dyn= -1 muR=0.50000E+00 muF=0.20000E+01 </weight>
> <weight id='1007'> dyn= -1 muR=0.10000E+01 muF=0.50000E+00 </weight>
> <weight id='1008'> dyn= -1 muR=0.20000E+01 muF=0.50000E+00 </weight>
> <weight id='1009'> dyn= -1 muR=0.50000E+00 muF=0.50000E+00 </weight>
> </weightgroup>
> </initrwgt>
> </header>
> <init>
> 2212 2212 0.65000000E+04 0.65000000E+04 -1 -1 244800 244800 -4 1
> 0.68083127E+03 0.26308972E+01 0.13094024E+04 0
> </init>
> <event>
> 4 0 0.13094024E+04 0.99286714E+02 0.75467711E-02 0.10637299E+00
> 21 -1 0 0 501 502 0.00000000E+00 0.00000000E+00 0.98147846E+02 0.98147846E+02 0.00000000E+00 0.0000E+00 0.9000E+01
> 21 -1 0 0 502 503 0.00000000E+00 0.00000000E+00 -.56701329E+03 0.56701329E+03 0.00000000E+00 0.0000E+00 0.9000E+01
> 6 1 1 2 501 0 -.67609886E+02 -.25682615E+02 -.32621134E+02 0.19032559E+03 0.17300000E+03 0.0000E+00 0.9000E+01
> -6 1 1 2 0 503 0.67609886E+02 0.25682615E+02 -.43624431E+03 0.47483554E+03 0.17300000E+03 0.0000E+00 0.9000E+01
> #aMCatNLO 1 0 0 2 4 0.24556574E+02 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'> 0.13094E+04 </wgt>
> <wgt id='1002'> 0.10308E+04 </wgt>
> <wgt id='1003'> 0.17079E+04 </wgt>
> <wgt id='1004'> 0.13458E+04 </wgt>
> <wgt id='1005'> 0.10561E+04 </wgt>
> <wgt id='1006'> 0.17613E+04 </wgt>
> <wgt id='1007'> 0.12422E+04 </wgt>
> <wgt id='1008'> 0.98168E+03 </wgt>
> <wgt id='1009'> 0.16134E+04 </wgt>
> </rwgt>
> </event>
> <event>
>
>
> ********************************************************************************
> I am confused a little. I can figure out the kinematic parts. But I am unable to figure out the weight information.
>
> <wgt id='1001'> 0.13094E+04 </wgt>
> <wgt id='1002'> 0.10308E+04 </wgt>
> <wgt id='1003'> 0.17079E+04 </wgt>
> <wgt id='1004'> 0.13458E+04 </wgt>
> <wgt id='1005'> 0.10561E+04 </wgt>
> <wgt id='1006'> 0.17613E+04 </wgt>
> <wgt id='1007'> 0.12422E+04 </wgt>
> <wgt id='1008'> 0.98168E+03 </wgt>
> <wgt id='1009'> 0.16134E+04 </wgt
>
> The above part is weight information i.e it is positive for positive weighted events and negative for negative weighted events. Is my understanding correct?
> And can you please point out any document for understanding the LHE format?
>
> Thanks,
> Soumyadip
>
> --
> You received this question notification because you are assigned to this
> question.

Hi,

Thanks for your detailed reply. That helped me a lot. Thanks again

Cheers,
Soumyadip

Thanks Paolo Torrielli, that solved my question.