PYTHIA Error in ProcessLevel::checkColours: incorrect colour assignment

Asked by mehdirahmani on 2019-05-15

Hello,

I am trying to feed my MadGraph generated lhe file to PYTHIA 8 to simulate CMS detector to the events:

cmsDriver.py Configuration/GenProduction/python/Pythia8HadronizerFilter_13TeV_cfi.py --fileout file:out_sim.root --mc --eventcontent RAWSIM --datatier GEN-SIM --conditions 93X_mc2017_realistic_v3 --beamspot Realistic25ns13TeVEarly2017Collision --step GEN,SIM --geometry DB:Extended --era Run2_2017 --filetype LHE --filein file:events.lhe --python_filename Private_SD.py --no_exec -n 10

and

cmsRun Private_SD.py

First I get the following warnings from PITHIYA:

PYTHIA Warning in SLHAinterface::initSLHA: ignoring MASS entries for id = [1,2,3,4,5,6,11,12,13,14,15,16,21,22,23,24] (SLHA:keepSM. Use id > 1000000 for new particles)
 PYTHIA Warning in SLHAinterface::initSLHA: ignoring MASS entries for id = [25] (m0 < SLHA:minMassSM)
 PYTHIA Warning in SLHAinterface::initSLHA: ignoring DECAY tables for id = [6,23,24,1,2,3,4,5,11,12,13,14,15,16,21,22] (SLHA:keepSM. Use id > 1000000 for new particles)
 PYTHIA Warning in SLHAinterface::initSLHA: ignoring DECAY tables for id = [25] (m0 < SLHA:minMassSM)

PYTHIA Warning in SLHAinterface::initSLHA: ignoring empty DECAY tables for id = [5000001,5000002,5000512,5000521,5000522] (total width provided but no Branching Ratios)

What is the meaning of the last warning?

Then at the end, I get this error:

Begin processing the 1st record. Run 1, Event 1, LumiSection 1 at 14-May-2019 14:20:17.701 CDT

PYTHIA Error in ProcessLevel::checkColours: incorrect colour assignment

PYTHIA Abort from Pythia::next: processLevel failed; giving up .

 *------- PYTHIA Error and Warning Messages Statistics ----------------------------------------------------------*
 | |
 | times message |
 | |
 | 10 Abort from Pythia::next: processLevel failed; giving up |
 | 10 Error in ProcessLevel::checkColours: incorrect colour assignment |
 | 1 Info from SLHAinterface::initSLHA: No MODSEL found, keeping internal SUSY switched off |
 | 1 Info from SLHAinterface::initSLHA: importing MASS entries |
 | 2 Warning in SLHAinterface::initSLHA: ignoring DECAY tables |
 | 2 Warning in SLHAinterface::initSLHA: ignoring MASS entries |
 | 1 Warning in SLHAinterface::initSLHA: ignoring empty DECAY tables |
 | |
 *------- End PYTHIA Error and Warning Messages Statistics ------------------------------------------------------*

Also the cross section appears to be zero after matching:

Overall cross-section summary
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Process xsec_before [pb] passed nposw nnegw tried nposw nnegw xsec_match [pb] accepted [%] event_eff [%]
0 3.789e-05 +/- 5.160e-08 0 0 0 10 10 0 0.000e+00 +/- 0.000e+00 0.0 +/- 0.0 0.0 +/- 0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 3.789e-05 +/- 5.160e-08 0 0 0 10 10 0 0.000e+00 +/- 0.000e+00 0.0 +/- 0.0 0.0 +/- 0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Before matching: total cross section = 3.789e-05 +- 5.160e-08 pb
After matching: total cross section = 0.000e+00 +- 0.000e+00 pb
Matching efficiency = 0.0 +/- 0.0 [TO BE USED IN MCM]

After filter: final cross section = 0.000e+00 +- 0.000e+00 pb
After filter: final fraction of events with negative weights = 0.000e+00 +- 0.000e+00
After filter: final equivalent lumi for 1M events (1/fb) = 0.000e+00 +- 0.000e+00

Can you help me with this?

Thanks,

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2019-05-15
Last reply:
2019-05-17

HI,

Please create a bug request since you will need to attach file if you want us to help you.

1) can you start by attaching your lhe file such that we can check the colour of the events. (this will allow to see if this is a PY8 bug or a MG5aMC one)

In case this is a MG5aMC bug, I will need to have the model file and the process in order to see what the problem is

Cheers,

Olivier

mehdirahmani (mehdirahmani) said : #2

Hi Oliver,

Thank you for your response. I created a bug report here: https://bugs.launchpad.net/mg5amcnlo/+bug/1829266

Thank you,

see bug report