Fix for FastSim decays of exotic-descendent SM particles decaying outside pipe

[sbein]

PR description:

This PR fixes a bug creating a problem first identified in

https://hypernews.cern.ch/HyperNews/CMS/get/famos/765.html

Jaebak found that some b- and d-mesons produced in the decays of exotic particles, which cross the beam pipe radius, have their decay performed twice, with sim hits created for each copy. This causes problems for some high-pT b-jets, as well as the MET in events that contain such jets. A few lines are added to ParticleManager.cc which results in FastSim deciding to not decay such particles further, and rather take only the original generator-determined decay trees. FastSim will still propagate these particles and create secondaries/material interactions, but it won't decay them.

PR validation:

This issue was also seen in signal events of a Bulk Graviton model G->HH, H->bb, where G has a mass > 1 TeV and H is the SM Higgs boson. The bug fix in this PR results in a stark improvement of the jet response at high pT:

https://www.desy.de/~mrowietm/fastsimplots/graviton_exotic/fastsim_comparison/comparison.png

By construction, neither the original problem or these changes will affect purely SM events.

This PR will need to be backported to any and all production releases that may be used for BSM signal MC production.

[cmsbuild]

-code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36122/26629

• This PR adds an extra 16KB to repository

Code check has found code style and quality issues which could be resolved by applying following patch(s)

• code-format:
  https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36122/26629/code-format.patch
  e.g. curl -k https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36122/26629/code-format.patch | patch -p1
  You can also run scram build code-format to apply code format directly

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36122/26655

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @sbein (Sam Bein) for master.

It involves the following packages:

• FastSimulation/SimplifiedGeometryPropagator (fastsim)

@ssekmen, @lveldere, @civanch, @mdhildreth, @cmsbuild, @sbein can you please review it and eventually sign? Thanks.
@matt-komm this is something you requested to watch as well.
@perrotta, @dpiparo, @qliphy you are the release manager for this.

cms-bot commands are listed here

[sbein]

please test

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-e84388/20575/summary.html
COMMIT: 3cdd06b
CMSSW: CMSSW_12_2_X_2021-11-16-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/36122/20575/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 42
• DQMHistoTests: Total histograms compared: 3320802
• DQMHistoTests: Total failures: 0
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 3320780
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 41 files compared)
• Checked 177 log files, 37 edm output root files, 42 DQM output files
• TriggerResults: no differences found

[sbein]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[sbein]

please test

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-36122/27046

• This PR adds an extra 20KB to repository

[cmsbuild]

Pull request #36122 was updated. @ssekmen, @civanch, @lveldere, @mdhildreth, @sbein can you please check and sign again.

[cmsbuild]

+1

Summary: https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-e84388/20895/summary.html
COMMIT: 2fe14d6
CMSSW: CMSSW_12_2_X_2021-11-30-1100/slc7_amd64_gcc900
User test area: For local testing, you can use /cvmfs/cms-ci.cern.ch/week1/cms-sw/cmssw/36122/20895/install.sh to create a dev area with all the needed externals and cmssw changes.

Comparison Summary

Summary:

• No significant changes to the logs found
• Reco comparison results: 6405 differences found in the comparisons
• DQMHistoTests: Total files compared: 41
• DQMHistoTests: Total histograms compared: 3042214
• DQMHistoTests: Total failures: 51280
• DQMHistoTests: Total nulls: 1
• DQMHistoTests: Total successes: 2990911
• DQMHistoTests: Total skipped: 22
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: -0.004 KiB( 40 files compared)
• DQMHistoSizes: changed ( 312.0 ): -0.004 KiB MessageLogger/Warnings
• Checked 175 log files, 37 edm output root files, 41 DQM output files
• TriggerResults: found differences in 2 / 40 workflows

[perrotta]

@sbein , if you sign this can be merged

[sbein]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @perrotta, @dpiparo, @qliphy (and backports should be raised in the release meeting by the corresponding L2)

[perrotta]

+1