Difference: Brenoorzari (39 vs. 40)

Revision 402020-10-01 - brenoorzari

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  I've been working with the FIMP model. Its simulation using MadGraph + Pythia + Delphes (going to call it just Delphes for simplicity) is not that good, since there are a lot of electrons/muons missing. Eduardo suggested that this is happening because of a generation cut (MadGraph or Pythia or even Delphes) that I am going to investigate. I am also trying to simulate it using the FullSim of CMSSW, but it might be harder.
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The Delphes generated events are in the folder ~/MG5_aMC_v2_6_6/FIMP_leptons_varying_width. An important macro is in the Delphes folder under the name Delphes_FIMP_hist.C and some results are in the folder Delphes_FIMP. 10000 events were generated for each decay width value and from run_01 to run_10 the decay length (c\tau) is approximately 100 mm, 200 mm, ..., 1000 mm and runs 11, 12, ..., 15 are 2 m, 4 m, 8 m, 16 m, 32 m respectively. Run_16 is a prompt (setting the decay width to 1) test. In MadGraph the syntax to simulate the events is p p > he~ HE~, and the F decay is being performed by Pythia through changes in the SLHA table. The tracks transversal impact parameter seems to be what I expected, however, the number of reconstructed (generated) electrons + muons that is around 1100 (7600) is much lower than the ~ 20000 expected from the Fs decay. I need to test a few things to find out where the problem is:
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The Delphes generated events are in the folder ~/MG5_aMC_v2_6_6/FIMP_leptons_varying_width. An important macro is in the Delphes folder under the name Delphes_FIMP_hist.C and some results are in the folder Delphes_FIMP. 10000 events were generated for each decay width value with m_{F} = 130 GeV, m_{s0} = 125 GeV and from run_01 to run_10 the decay length (c\tau) is approximately 100 mm, 200 mm, ..., 1000 mm and runs 11, 12, ..., 15 are 2 m, 4 m, 8 m, 16 m, 32 m respectively. Run_16 is a prompt (setting the decay width to 1) test. In MadGraph the syntax to simulate the events is p p > he~ HE~, and the F decay is being performed by Pythia through changes in the SLHA table. The tracks transversal impact parameter seems to be what I expected, however, the number of reconstructed (generated) electrons + muons that is around 1100 (7600) is much lower than the ~ 20000 expected from the Fs decay. I need to test a few things to find out where the problem is:
 
  • Change the s0, F mass difference to see if events that contain leptons with higher p_T are sufficient (this would point to a generator cut that might be caused by Madgraph, Pythia or Delphes)
  • Check the number of s0 generated particles (if this number is 20000, this would point only to Pythia or Delphes, I guess)
  • Check the reco and gen leptons p_T (this is not that useful since I would expect only leptons that already passed MadGraph lepton p_T restriction)
  • Check gen particle status (from Pythia log they must be +/- 23)
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The number of generated s0 with status 23 is equal to the number of generated electron + muon with status 23. The status of every s0 is equal to 23 (and there are status=0 that I don't know what it means). MadGraph has a selection cut on leptons p_T of 10 GeV. This shouldn't be a problem since MadGraph would then generate events that have laptons p_T around this value. Delphes imposes an efficiency of 0 in reco leptons that have p_T < 10 GeV (great issue concerning the mass difference that I set). Gen leptons have very low/high p_T, and reco ones have p_T > 10 GeV from the cut I described before.

In run_17 I set m_F = 300 GeV and m_{s0} = 125 GeV with c\tau ~ 200 mm to see if the problem with the leptons would continue (I didn't change any generation restriction in Madgraph or Pythia or Delphes).

 

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