Issues with MuonFilter/ 50 GeV cutoff

FCCSW
1

I am attempting to generate data and events by changing the Pythia card from describing the standard model ffbar to ZH event to a beyond standard model ffbar to A3H1 or a Higgs and pseudo-Higgs particle and observing how the resulting data generated changes with the mass of the A3 particle.

My questions rise from issues I am experiencing in this process:

  1. I cannot seem to find the Gen level particle data, only the reconstructed particle data for each generated set of collisions
  2. When a set number of events is generated, while I move the mass of the A3 particle downwards, rather than the mass moving down in the histograms to indicate overall mass decreasing for each event, there is a sharp spike at 50 GeV that does not change. Is there some kind of muon filter or other code I would need to change or implement to fix this issue?
2

Hi Hayden, could you share the code to reproduce this problem?
Thanks,
Valentin

3

Of course.

So I followed the FCC starterkit section 2.3 pretty closely:
(2.3. FCC: Getting started with analysing simulated events — FCC Starterkit Lessons documentation)
Where you create analysis.py, finalSel.py, and plots.py. The code for them is on the website, but the main changes I’ve made to anything would be the Pythia card that is directly downloaded in part 2.2 of the tutorial.

The pythia card (called p8_noBES_ee_ZH_ecm240.cmd) looks like the following after the BSM changes:

Random:setSeed = on
Main:numberOfEvents = 10000 ! number of events to generate
Main:timesAllowErrors = 5 ! how many aborts before run stops

! 2) Settings related to output in init(), next() and stat().
Init:showChangedSettings = on ! list changed settings
Init:showChangedParticleData = off ! list changed particle data
Next:numberCount = 100 ! print message every n events
Next:numberShowInfo = 1 ! print event information n times
Next:numberShowProcess = 1 ! print process record n times
Next:numberShowEvent = 0 ! print event record n times

Beams:idA = 11 ! first beam, e+ = 11
Beams:idB = -11 ! second beam, e- = -11

! Vertex smearing :
Beams:allowVertexSpread = on
Beams:sigmaVertexX = 9.70e-3 ! 13.7 mum / sqrt2
Beams:sigmaVertexY = 25.5E-6 ! 36.1 nm / sqrt2
Beams:sigmaVertexZ = 0.64 ! 0.64 mm

! 3) Hard process : ZH at 240 GeV
Beams:eCM = 240. ! CM energy of collision
! HiggsSM:ffbar2HZ = on
! HiggsBSM:all = on
Higgs:useBSM = on
HiggsBSM:ffbar2A3H1 = on

! 4) Settings for the event generation process in the Pythia8 library.
PartonLevel:ISR = on ! initial-state radiation
PartonLevel:FSR = on ! final-state radiation

! 5) Non-standard settings; exemplifies tuning possibilities.
! 25:m0 = 125.0 ! Higgs mass
! 23:onMode = off ! switch off Z boson decays
! 23:onIfAny = 13 ! switch on Z boson decay to muons
36:m0 = 30 ! A3 mass
36:onMode = off ! Switch off A3 decays
36:onIfAny = 13 ! Switch on A3 decay to muons

So the issue is that with changing the Pythia card, and changing the pT values to not restrict anything, once your regenerate the events there is no clear way to locate the gen-level particles, only the reconstructed ones. Also, the data does not move with the mass of the particles that are colliding. The histograms do not behave expectedly if you lower the mass of the A3 particle being used here.