Heavy ions in MG5 for MM production whithin photon fusion process

Asked by Branzas Horea Florin on 2021-03-16

Hello everyone!

I try to do simulations in MG5(v2.6.7) for photon fusion for production of magnetic monopoles in heavy ion collisions for example in Pb Pb. So i tried to use this pdf for heavy ions EPPS16nlo_CT14nlo_Pb208. The input set commands are:

import model mono_spinzero/
generate a a > mm+ mm-
output simulari/monopoles_13tev_spinzeroPb
launch
analysis=madanalysis5
set lpp1 2
set lpp2 2
set dynamical_scale_choice -1
set fixed_couplings False
set param_card mass 25 125
set decay 4110000 0.000000e+0
set gch 1 1.0
set pdlabel lhapdf
set lhaid 901300
set MMM 1000
set ebeam1 2560*208
set ebeam2 2560*208
set nevents = 10000
launch
But I encounter certain errors:

INFO: Update the dependent parameter of the param_card.dat
Generating 10000 events with run name run_02
survey run_02
INFO: compile directory
INFO: Using LHAPDF v6.1.6 interface for PDFs
compile Source Directory
Using random number seed offset = 30
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P1_aa_mmpmmm
INFO: Idle: 1, Running: 0, Completed: 0 [ current time: 12h49 ]
INFO: Idle: 0, Running: 0, Completed: 1 [ 2.4s ]
INFO: Idle: 0, Running: 0, Completed: 1 [ 2.4s ]
INFO: End survey
refine 10000
Creating Jobs
INFO: Refine results to 10000
INFO: Generating 10000.0 unweigthed events.
INFO: Effective Luminosity 15.7045451571 pb^-1
INFO: need to improve 1 channels
Current estimate of cross-section: 764.11 +- 15.308
    P1_aa_mmpmmm
INFO: Idle: 6, Running: 6, Completed: 0 [ current time: 12h49 ]
INFO: Idle: 5, Running: 6, Completed: 1 [ 3.9s ]
INFO: Idle: 0, Running: 6, Completed: 6 [ 8.2s ]
INFO: Idle: 0, Running: 1, Completed: 11 [ 12.1s ]
INFO: Idle: 0, Running: 0, Completed: 12 [ 12.7s ]
INFO: Combining runs
INFO: finish refine
refine 10000
Creating Jobs
INFO: Refine results to 10000
INFO: Generating 10000.0 unweigthed events.
INFO: Effective Luminosity 15.5197165065 pb^-1
INFO: need to improve 0 channels
Current estimate of cross-section: 773.21 +- 3.0676
    P1_aa_mmpmmm
INFO: Idle: 0, Running: 0, Completed: 0 [ current time: 12h50 ]
INFO: Combining runs
INFO: finish refine
INFO: Combining Events
  === Results Summary for run: run_02 tag: tag_1 ===

     Cross-section : 773.2 +- 3.068 pb
     Nb of events : 10000

INFO: Running Systematics computation
INFO: Idle: 0, Running: 4, Completed: 0 [ current time: 12h50 ]
WARNING: program /usr/bin/python2.7 -O /home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/simulari/monopoles_13tev_spinzeroPb/bin/internal/systematics.py unweighted_events.lhe.gz ./tmp_1_unweighted_events.lhe.gz --mur=0.5,1,2 --muf=0.5,1,2 --pdf=errorset --start_event=2500 --stop_event=5000 --result=./log_sys_1.txt --lhapdf_config=/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/lhapdf6/bin/lhapdf-config launch ends with non zero status: 1. Stop all computation
INFO: Idle: 0, Running: 1, Completed: 3 [ 1m 34s ]
INFO: Running Systematics computation
INFO: # events generated with PDF: EPPS16nlo_CT14nlo_Pb208 (901300)
INFO: #Will Compute 141 weights per event.
INFO: # currently at event 0 [elapsed time: 0.046 s]
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
<event>
 4 1 +7.7321000e+02 2.52275400e+03 7.29740600e-03 7.88553600e-02
       22 -1 0 0 0 0 +0.0000000000e+00 +0.0000000000e+00 +3.6082000513e+04 3.6082000513e+04 0.0000000000e+00 0.0000e+00 -1.0000e+00
       22 -1 0 0 0 0 -0.0000000000e+00 -0.0000000000e+00 -2.0608233293e+02 2.0608233293e+02 0.0000000000e+00 0.0000e+00 -1.0000e+00
 -4110000 1 1 2 0 0 +5.0380315717e+02 +2.2606344750e+03 +1.1050166932e+04 1.1334481686e+04 1.0000000000e+03 0.0000e+00 0.0000e+00
  4110000 1 1 2 0 0 -5.0380315717e+02 -2.2606344750e+03 +2.4825751248e+04 2.4953601161e+04 1.0000000000e+03 0.0000e+00 0.0000e+00
<mgrwt>
<rscale> 0 0.25227536E+04</rscale>
<asrwt>0</asrwt>
<pdfrwt beam="1"> 1 22 0.67762443E-01 0.25227536E+04</pdfrwt>
<pdfrwt beam="2"> 1 22 0.38702206E-03 0.25227536E+04</pdfrwt>
<totfact> 0.71354244E+01</totfact>
</mgrwt>
</event>

Command "generate_events run_02" interrupted with error:
Exception :
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in '/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/simulari/monopoles_13tev_spinzeroPb/run_02_tag_1_debug.log'.
Please attach this file to your report.
INFO: storing files of previous run
INFO: Done
INFO:
INFO:
quit
INFO:
quit

Before the simulation i did:

export LHAPDF=/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/lhapdf6/share/LHAPDF

export PATH=$PATH:</home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/bin

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/lhapdf6/lib

printenv | grep lhapdf -i

LD_LIBRARY_PATH=/home/branzashoreaflorin/root_v6.22.00.Linux-ubuntu19-x86_64-gcc9.2/root/lib:/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/lhapdf6/lib
LHAPDF=/home/branzashoreaflorin/Desktop/MG52.6.7/MG5_aMC_v2.6.7/MG5_aMC_v2_6_7/HEPTools/lhapdf6/share/LHAPDF

Before of that i used as pdf LUXqed (lhaid 82000) and everything was fine but not with 901300 pdf. I mention the fact that I installed this pdf manually. Are the input commands correct for this type of process? Many thanks.

Best regards,
Horea

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2021-03-16
Last reply:
2021-03-24

Hi,

The first issue that I have to comment is the meaning of lpp=2. Which makes the field "pdlabel" and "lhaid" to not be used.
So you need to decide to either run:
set lpp 2
or do
set lpp 1
set pdlabel lhapdf
set lhaid 901300

For lpp 2 you will get elastic photon, while for lpp1 you will get in principle inelastic photon but you need to check the paper of the according PDF set since different collaboration are handling differently photon PDF some collaboration include inelastic as well.

By default lpp 2 is set for proton beam and not for heavy ion beam. Starting with version 2.7.0, we started the support for heavy beam in that mode.
For that you need to specify in the run_card the mass of the ion and the number of proton.

#*********************************************************************
# Heavy ion PDF / rescaling of PDF *
#*********************************************************************
  1 = nb_proton1 # number of proton for the first beam
  0 = nb_neutron1 # number of neutron for the first beam
  -1.0 = mass_ion1 # mass of the heavy ion (first beam)
# Note that seting differently the two beams only work if you use
# group_subprocess=False when generating your matrix-element
  1 = nb_proton2 # number of proton for the second beam
  0 = nb_neutron2 # number of neutron for the second beam
  -1.0 = mass_ion2 # mass of the heavy ion (second beam)

So in short, I would not trust any of your result, even those who are not crashing.

For the crash per se, since the code is very old, the best is to test if you face the same issue in the latest version of the code, which is anyway needed in your case if you want to use the feature that you are looking for.

Cheers,

Olivier

Dear Olivier

First of all i want tot thank you for your help.
This time I used these commands as input for MadGraph5 v 2.8.2:

import model mono_spinzero/
generate a a > mm+ mm-
output simulari/monopoles_13tev_spinzeroPb
launch
analysis=madanalysis5+
set PbPb
set lpp1 1
set lpp2 1
set dynamical_scale_choice -1
set fixed_couplings False
set param_card mass 25 125
set decay 4110000 0.000000e+0
set gch 1 1.0
set pdlabel lhapdf
set lhaid 901300
set MMM 1000
set ebeam1 = 2750*208
set ebeam2 = 2750*208
set nevents = 10000

The output is this:
INFO: Update the dependent parameter of the param_card.dat
Generating 10000 events with run name run_01
survey run_01
INFO: compile directory
INFO: Using LHAPDF v6.3.0 interface for PDFs
compile Source Directory
Using random number seed offset = 21
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P1_aa_mmpmmm
INFO: Idle: 1, Running: 0, Completed: 0 [ current time: 14h29 ]
INFO: Idle: 0, Running: 0, Completed: 1 [ 13.3s ]
INFO: Idle: 0, Running: 0, Completed: 1 [ 13.3s ]
INFO: End survey
refine 10000
Creating Jobs
INFO: Refine results to 10000
INFO: Generating 10000.0 unweighted events.
sum of cpu time of last step: 13 seconds
INFO: Effective Luminosity 1.2e+103 pb^-1
INFO: need to improve 0 channels
Survey return zero cross section.
   Typical reasons are the following:
   1) A massive s-channel particle has a width set to zero.
   2) The pdf are zero for at least one of the initial state particles
      or you are using maxjetflavor=4 for initial state b:s.
   3) The cuts are too strong.
   Please check/correct your param_card and/or your run_card.
Zero result detected: See https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/FAQ-General-14
INFO:
quit

I don't have much experience in MadGraph and I'm trying to learn it more and more. Thanks again for your help

Best regards,
Horea

Hi,

If you look at the info-file of your PDF set:
https://lhapdfsets.web.cern.ch/current/EPPS16nlo_CT14nlo_Pb208/EPPS16nlo_CT14nlo_Pb208.info
or to the associated paper:
https://arxiv.org/pdf/1612.05741.pdf
you will see that they are not photon PDF in that pdf set, so according to that PDf set, the probability to have a photon as part of the proton is zero. Consequently you are in the second case here, your pDF forbids such process to occur and therefore the cross-section is zero.

Also note that your command
set PbPb is doing the following:
INFO: modify parameter lpp1 of the run_card.dat to 1
INFO: modify parameter lpp2 of the run_card.dat to 1
INFO: modify parameter nb_proton1 of the run_card.dat to 82
INFO: modify parameter nb_neutron1 of the run_card.dat to 126
INFO: modify parameter mass_ion1 of the run_card.dat to 195.0820996698
INFO: modify parameter nb_proton2 of the run_card.dat to 82
INFO: modify parameter nb_neutron2 of the run_card.dat to 126
INFO: modify parameter mass_ion2 of the run_card.dat to 195.0820996698

When combine with a PDf set, we will do PDf rescaling (lpp=1) assuming a PDF from the proton.
So this is not designed to be used with the above PDf set where all the effect of many proton/neutron are handle internally to the PDF set.

Sorry that such part of the computation is not that user friendly. Lead collision is not our first focus since in general Argantur is more designed for such type of physics.

Cheers,

Olivier

PS: so I guess that the syntax that should fit your need is:
import model mono_spinzero
generate a a > mm+ mm-
output simulari/monopoles_13tev_spinzeroPb
launch
analysis=madanalysis5
set PbPb
set lpp1 2
set lpp2 2
set fixed_scale 2000
set fixed_couplings False
set param_card mass 25 125
set decay 4110000 0.000000e+0
set gch 1 1.0
set MMM 1000
set ebeam1 = 2750*208
set ebeam2 = 2750*208
set nevents = 10000

Hi Olivier.

Thanks for the help. I managed to get the cross sections with the pdf set LUXqed (set lhaid 82000) for Pb Pb. At this point I am trying to find out how I could change the impact parameter for heavy ion collisions into peripheral and ultra peripheral collisions. How can I do this in MadGraph5?

Best regrads,
Horea

You do not have any control on that in MG5aMC.

Cheers,

Olivier

> On 24 Mar 2021, at 17:10, Branzas Horea Florin <email address hidden> wrote:
>
> Question #696091 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/696091
>
> Branzas Horea Florin posted a new comment:
> Hi Olivier.
>
> Thanks for the help. I managed to get the cross sections with the pdf
> set LUXqed (set lhaid 82000) for Pb Pb. At this point I am trying to
> find out how I could change the impact parameter for heavy ion
> collisions into peripheral and ultra peripheral collisions. How can I do
> this in MadGraph5?
>
> Best regrads,
> Horea
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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